This tagging's OK. It's not the “wrong” game tag. We use [dungeons-and-dragons] when the question isn't about any one edition in the series, which is normal for history questions about the series, but can also be the case for other questions.
In this case knowing it's D&D is relevant, but we didn't care which edition when it was asked because just knowing it was any edition of D&D was enough information to answer it.
Like any game system, D&D introduces a set of gameplay expectations, social dynamics, and a specific set of tools in-game and at a general game management level to help resolve the issue. Other games don't have the same set of those things. Knowing we were working with what D&D generally brings to the table was enough for us to work with. (Consider that we'd have very different responses if this was Monsterhearts or Apocalypse World, which have explicit mechanics and expectations around X-rated content, where D&D expects none whatsoever.)
For many social issues, the exact edition isn't going to affect things beyond the mere knowledge it's D&D, so we didn't need to ask specifically for the edition. There are definitely some social contract variations between different editions though (e.g. expectations around the GM vs player relationship, and how adversarial it is, have changed over time) so in those situations we're likely to ask for more detail.
So: knowing & tagging it's D&D was appropriate and good enough.
Asking them to provide their edition as you've done in comments is fine, as that's a standard request for information. They might provide it or not. If things remain just as they are though, I think that's OK.