I think he is referring to your text at the top of this post, as it is not proper English.

As another data point, I would disregard your application immediately upon being asked to 'Sing In' and 'Sing Up', which is clearly a rookie typo/shows a lack of attention to detail.

https://i.imgur.com/Pwwmsda.png

Regardless of what anyone says, keep going at it and get better every day.

You would disregard a non-native PROGRAMMER because on the front page of his side-project says"Sing" instead of "Sing". That's extremely harsh. I might even consider it stupid.

I think he is applying as a developer, not as an English teacher.

ps. I've read a lot of comments like this one, in various threads here and on reddit. I really wonder if the people who make those remarks are equally austere with themselves.

Yes, I would. Typos on github readmes and HN posts are trivial, however, any blemish on a site built solely to showcase accomplishments, skills, experience, and attributes, regardless of how small the blemish is, reflects negatively on the author. Of all sites, this site should be top-notch.

As for your PS, yes.