The tweets may have just been jokes, but even the jokes people make reflect their thoughts, opinions and values. You can tell a lot about a person by what they think is funny when they’re letting their hair down. If Blomberg’s values are antithetical to Ursinus’s institutional values, as presumably they are, I think the Ursinus community is quite right to want him gone.
Also, the president of the board of an institution of higher education should presumably be of at least normal intelligence and this guy is clearly an idiot. The Internet is forever. Don’t put anything in an email or a text, much less a tweet, that you wouldn’t be happy to see on the front page of the New York Times. It’s not that tough a concept.