It’s fine, as long as the time he submitter spent to write a decent bug report is worthless to you.
If you're not working on a bug, then, by definition, it's not taking up your time.
Some people are just obsessive about not wanting to look like they have open bugs on their project. But closing tickets and fixing bugs are not the same thing.
You can't measure how many bugs you have, but you can measure how many bug reports you have. ;D
Triaging an endless list is very costly.
I do agree with the idea that if you expect your project to be public (and not just something you did that you'll share if somebody wants) it is a cost you are expected to take. But it's wrong to pretend it's free.
If maintainers feel like they need to close tickets only to keep order, than that's a problem with the tooling: tickets should only be closed if they're malformed, solved, or (arguably) wontfix.
Oh, yes. Yes it is!
I think you were downvoted because the first part of your answer is wrong, but this one hits right on the mark.