Some people might still be subscribed to it, so you will reach an audience. I never check whether moderators are active before posting.

Is it full of spam because it’s unmoderated or is it just empty. If it’s just empty but has a good amount of subs just start posting. A lot of times the community can police itself and if you need a moderator if it becomes more active then reach out the the instance admins that the community is hosted on.

I think many keep their moderation accounts separate from the account they use to post and comment. Checking their comment history doesn’t mean much.