Efrem, Discord, publically making fun of people for being wrong in AdminHelps

[CaptainBravo]

In this situation there was clearly a preexisting communication between the player and efrem, efrem dispelled their mistake (which is not being called into question- there's no implication here that a-helping was a mistake or is being ridiculed). The player seems to be conveying complaint in public discord that contradicts what they were told by the admin, the admin is responding by stripping their credibility.
That's kind of how competing claims work.

Your analogy to how mentors are meant to treat the information in Mhelps is relevant, but not all-encompassing.
Admins (generally, sorta) have the additional prerogative to share whatever sensitive information they see fit *so long as that information doesn't impact other admins* - we do this with sanitised logs, and in fact, while responding to APMs regularly.

Sharing the equivalent of "You know that's not true because *we had a conversation (A-helps) about this not long ago*" is not outside that scope in my opinion.
If players want to vent at/about each other, they ought to at least not be deliberately misinformed.
I'm really not seeing anything out of the ordinary or particularly harmful from Efrem here.

Setting this straight: There was no ahelp conversation. I don't like feeding players information about the round in ahelps because I don't like checking whether they're alive or dead-but-coming-back or whatever the case may be, and because this game isn't about getting closure that everything that happened in a round was kosher.

I simply saw that nothing was out of the ordinary and chose not to say anything. I still feel this was right because if I can't trust someone not to fume and slander someone in every available channel then I definitely don't trust them to know behind-the-scenes things like "oh yeah no that guy was an antag".

That said, the lack of being told that you're wrong in an ahelp is never a reason to come onto Discord and start blasting salt about whatever someone else did in-game. If you try to mom and dad your hurt feelings and drag them into spaces where another player might not even be around to defend what they did or set it straight, I'm blastin back. Not sorry.