If it was offensive (sounds like it probably was) and you shared it, and the TD knows your facebook "alias" is tied to you, I'd say it's their right to do as they please. Just because you have a facebook account with a fake name doesn't mean you're immune to consequence.

Editing the photo to make it look like you were the original poster is a little sheisty, I'll admit, but if you were sharing it (assuming for laughs) then idk if you have a super compelling defense. That's like repeating a dirty joke and trying to blame the person you heard it from.

That said, it's hard to judge from the outside when we don't know what was actually posted.. the fact that you didn't share it here kind of suggests that you know it wasn't appropriate, though.