It depends. Personally I'm happy to have my grammar corrected, as long as it's done with good intentions. Perhaps I'm in the minority. I do normally avoid correcting others though, since it's difficult to tell whether someone will be receptive (or offended).

Op mentioned they’re from HK, it wasn’t a call out as much as a helpful tip to a (probably) not native English speaker. If anything, your comment was far less necessary and rude.

It's not necessarily a waste of time. The poster says they're from Hong Kong, English could be their second language. They may not realize the mistake and if no one points it out they may never have the chance to learn.

I would much rather be told how to communicate effectively by a native speaker than be defended by a white knight SJW who thinks I'm too sensitive about my command of the language to take constructive criticism. Someone should make an SJW version of the C compiler that just compiles random stuff with undefined behaviors instead of correcting me with its trigger-inducing error messages.