I'd like to think Starfleet didn't make that guy resign just because of his half-romulan deal
The problem is Simon Tarses knew he was half-Romulan, rather than half-Vulcan. He lied on his application to Starfleet. That's why he would have been punished.
Yeah, I have to say Tarses wouldn't have been booted. One he didn't lie out of malice, but to save himself from persecution... justifiably when Satie comes after him the way she did. Picard took up for him that episode, and I can't believe he wouldn't pull the same strings that he did for Sito.
In the novels he later became a full doctor and worked on DS9. So he was never kicked out there.