I think it's laughable what some people perceive as transgressions... A guy like Alec Ogletree, drafted by the Rams in the late first this past April, had real character concerns, multiple arrests, suspensions from his team, drug charges... And very few people (outside draftniks, UGA fans, and NFL GMs) had a clue.
Now Johnny Manziel gets hammered one night at party, and has a few unscrupulous tweets, and people are questioning whether NFL GMs would take the risk.
That's not serious character concerns. Meaning this isnt liable to get him arrested, it doesnt showcase a pattern of horrific and frightening behavior, it doesnt indicate anything beyond him being a kid and he has as much chance to "grow up" as anybody else whoever went to college. ultimately it's the same crap every college kid does. They overdo it as they figure out their limits, as they grow up 99% of them figure it out.
Now if you want to argue if his QB talents warrant a 1st round pick, that's a different argument. One that you can debate endlessly at this point, as there was only one year of tape out there to watch of him as a freshman.