See, the thing is, I can't find any improvements because the entire premise feels to me inherently propaganda-ish. I'm sorry, I can try to break it down into more detail, but I suspect that it will be unfixable for me.

I'm going to try to rank the main bullet points of my discomfort in order of how important they are, most to least.

• I feel very uncomfortable with the entire dynamic of a 'right way / wrong way' pair. Partly this is because of individual cases where people using it ticked me off, but fundamentally it is that the idea of the character 'who exists solely to be wrong' makes me uncomfortable. Even if he isn't a strawman, he makes me uncomfortable.
• • The spiritual equality of humanity is a fundamental... not religious but sub-religious belief for me? The kind of thing you make religion out of, or that determines which religions feel right to you? Starting with the statement "all people are equally valuable" implies "in representative fiction, all people ought to be equally valuable to the extent to which the work is attempting to be representative of people's mental and spiritual states." That's why, e.g., the Sharpe series will never be a favorite of mine - because there are all these horrible people who exist so the protagonist can be better than them.
• • Worse: My natural instinct is always to support the underdog. There's a part of my brain that thinks that the underdog must be right, purely because he is the underdog. And the ultimate underdog is the one where the entire universe is opposed to him; the character created to be wrong therefore has the highest level of underdog power humanly possible, far exceeding normal victims, who at least have the author's sympathies, or actual villains, who might win partial victories or get awesome scenes; the Bad Example is doomed by the nature of the universe he lives in, and is therefore the character my underdog instinct must make me support.
• • The only exception I can think of to this general principle is Yudkowsky's "Inadequate Equililbria," but that's because Simplico gets some very good lines; he genuinely makes good arguments for his position, even though the author disagrees with it. But you, in your situation, can't give the bluebird better lines, because you are writing an extremely short, extremely simple parable, and witty dialogue or complicated back-and-forth arguments would spoil the whole effect. 

• The general style of it - soft, beautiful art, accompanied by largely one-syllable words in that specific kind of style and formatting - immediately suggested something aimed at small children. (2-5) This, to me, implied two things - first, that it would treat its audience like children, and second, that the material would be presented for children. But:
• • I didn't like being treated like a child when I was a child, and I still feel lingering discomfort about anything that treats me like a child.
• • I dislike simple analyses of complicated topics, and by this work's nature, it has to be a simple analysis, because you're either aiming it at small children or making it look as if you are.
• • I dislike the idea of giving propaganda to small children, so I'm going to feel more negatively about any propagandistic elements that exist; this is a magnifier, not a source, but it's definitely a magnifier.

• I am not, personally, a vegetarian. I'm inside EA, but only inside the first circle; my belief in the fundamental equality of humanity, combined with historical knowledge that helps me realize how terrible the lives of people in the third world are, leads me to believe that obviously third-world charity is more important than first-world charity, and clearly other people who are worse off can use the money more than I can, I have a reasonably comfortable life even by first-world standards. And I worry about X-risk literal and metaphorical because history is terrible, and I see insufficient reason to assume it won't continue to be. But I have not yet been convinced of animal rights even to the extent of vegetarianism. I agree that I ought to carry out a serious investigation; the serious investigation is currently in the queue behind a serious investigation of what religion, if any, is true, and I am not seriously altering my actions prior to the investigation for Pascal's Mugging style reasons. But as a result of that, any attempt to preach vegetarianism to me is automatically going to trigger my brain's 'defend beliefs' module, which will run a quick check to determine if this is the kind of argument I need to take seriously or if it (a) puffery or (b) emotional manipulation, and almost any argument that doesn't fit the 'serious analysis, making strong arguments, responding to my concerns, and logically explaining why I am wrong' pattern is going to end up in one bin or the other.
• • This wound up in the 'emotional manipulation' bin, partly because I'd already been feeling emotionally manipulated by the first few panels, partly because of the aimed-at-children style, and partly because it felt as if it was executed with too much craft to be puffery. But I dislike emotional manipulation, vegetarianism is a political cause, and emotional manipulation for a political cause is propaganda.
• • So, stacked on top of all my other issues, this resulted in my initial comment, an attempt to convey 'this strongly didn't work for me' while attempting to be as polite and informative as possible.

Again, I'm sorry. I can explain what my reactions were, I can analyze and dissect them, but I can't explain how the story could be altered to avoid triggering them because the problems seem to me to be fundamental to the nature of the artwork, and I cannot imagine an alternate design for the artwork that would not feel to me as if it shared these problems. This doesn't mean it's impossible, but it means it is beyond my level of skill to achieve. 

Thanks for the comments! The urgency argument makes sense. I'm not sure if I'll end up changing things, but I'll consider it, and thanks for pointing this out!