Every good open source project I've seen will happily accept and merge refactoring pulls, as long as the refactoring:

-Actually makes the code cleaner.

-Reduces redundancies.

-Above all, actually results in there being less code than there was before.

If you can achieve clean code + negative lines of code after a refactor, with identical functionality, they'd be fools to not merge it.

It's possible the refactors you submitted didn't meet these requirements. Or the project owners simply were too possessive of the code they wrote with their own fingers.