I mean I don't know 100% what happened, but from our perspectives it was a bit different.
Rocky came to us saying Tyr is blackmailing you for your staff rank to get into a Discord in which people were discussing a Overthrow in. (You had apparently accidentally frozen him and he was telling you unless you want to lose your rank to staff abuse, you will give him what he wants)
Rocky was pushing hard to get Tyr banned before any proof was found.
Tyr would probably be perma'd if it was found out to be true.
Rocky and Tyr were asked to gather up proof (Rocky was asked because you weren't in TeamSpeak at the time and he had some way of talking to you) and Tyr came forward with some message saying he was really blackmailing you with the fact that he knows you're OTing and the only way you'll be pardoned is if you gave the overthrow discord away.
Rocky interrupted in the middle of Shepard reading Tyr's messages to report that you messaged him apologizing and saying generally the same thing.
You were deemed bad because the thing you lied about was about to get someone perma banned and Shepard deemed that "whatever rank he is, hes not it now".
Not sure if at the time he meant demotion by 1 rank or what, but I guess this is all why you weren't really given a chance to give evidence is because from their perspectives they received evidence from the person you were being "blackmailed" by and Rocky who had received messages from you, so they assumed you had no more evidence.
I don't know, I wouldn't have all out demoted you considering you came forward and admitted you were wrong and didn't push for Tyr to get into any real trouble, your previous behavior on the server, and how this is your first instance. I might have just demoted you down to Moderator and slap a staff strike on there, so you'll realize the severity of your actions. After a bit, give you Senior Moderator back if you didn't do anything else bad and proved you only mean well for the server. Too late now I suppose.