I doubt using typos to discredit other people's work or opinions is rational or polite. I didn't write that extension, but he/she could just be a non-native speaker like me. What's your problem with people who doesn't speak and write in your native language? Can you write in mine, 100% error free?
I have absolutely no problems with people who don't speak and write in my native language. You're misinterpreting my comment, which was intended to be constructive, and responding with an ad hominem attack by suggesting that I am bigoted.
I think it's quite rational to suggest that work is of dubious quality if something as important as the tagline or elevator pitch contains errors that should be caught by a proofreading or spell-checker. The author spelled it correctly in the title and elsewhere in the text, so it's a simple error, not a lack of knowledge. It would be impolite to not suggest improvements, because the author could use my help.
A rational response to my comment would be exactly as you have done with drv's comment: "Fixed typo, thanks!"
*fixed typo, thx