Lots of information has come out recently about Sitton's behavior and personality. It's a very consistent picture, he is the gruff, plain-spoken guy who we've seen for 8 years. Bottom line is he is the good teammate that TT testified to, he cares about winning first and foremost.
I do think it is credible that MM perceived he could become a problem in the future. I doubt that was a primary consideration, but judge for yourself.