People are taking this tweet out of context IMO. Charles has even tweeted before that he likes that A&M is pushing hard for him because all of the A&M fans make fun of him for not having an offer. I personally think this was just a dig at A&M fans again (he makes fun of them often on Twitter). The only reason he deleted the tweet was due to the fact that Longhorns were melting down and A&M fans were acting like their normal jackass selves. I don't blame him for deleting the tweet the way people were behaving.
Some of his comments about the team in recent weeks are far from "being off the boat".