I challenge the initial framing of there being a choice to be made between "explicitly atheist" and "respectful to theists." One can, in fact, choose to be both at once.

But, yes, I would agree that not everyone makes that choice.

This isn't unique to atheists, incidentally... many explicitly theist communities choose not to be respectful to other theists, in much the same way.

In any event, I would agree that if there are people around who consider respecting their fellow group members an actively bad thing if those group members aren't thinking correctly enough, then at some point I've got to make a choice about what I value more.