They probably know.
If it’s me, then I pretty much know what I post. I sometimes post without thinking, but then it’s my own problem- I usually reread my posts and wince as they come back to bite me later.
If not, the same sense of privacy that keeps you from going over to them outright probably gives that poster a framework of what he/she considers proper to tell people.
If it’s me, just shoot me an email or send me a text- if you really know me well enough to figure out which anon poster I am, you’ll know one or the other. If you think you know who I am, then tell me; I just don’t want anyone asking me if they don’t know for sure, like, “Are you writersoul? Or maybe you’re Health? No, you’re probably PBA, right? For sure, so the type.” If you know who I am for sure then there’s nothing I can do about it already.
But probably they know what they’re doing and if they don’t it’s not your business to say.
And whether it’s me or not, leave this to email or text. In-person is just awkward. (I know this from experience, unfortunately…)