I don't think it matters in his tweet whether he likes Sanders or not. I'd say he doesn't, since I don't think he thinks much of some of Sanders' stances and ambitions, and there's been quite some banter from Sanders towards Trump. But alas, that's not what matters in the tweet.
He's pointing out the disgusting situation of the democrat primaries which are quite a sad sight. Just look at the mess in Nevada(it's similar in scale with what happened in Colorado for the republicans). He also tells Sanders to run as independent, but I doubt he was serious or expects anything out of it due to the Forrest Gump reference

Overall just a shitpost, but a very funny shitpost.
Regardless what Sanders decides and if he endorses Clinton or not, quite a number of his supporters have already been alienated by Clinton.