But that's the thing. Any criticism of Israel requires a 2-page disclaimer in order to make it perfectly clear your criticisms do not in anyway support antisemitism. I have not found a clear criticism of Israel on Twitter that did not require, at least, 10 additional tweets.
It's a poor medium for any academic to use. I fail to understand why he would in the first place. Intellectual debates are quite dry and nuanced. 2 things that microblogs do really poorly.
For all Twitter's shortcoming as a means for making nuanced arguments and the sensitivities of commenting on things Israelis and Palestinians have done without being accused of rationalising the excesses of the other side, it's not exactly difficult to convey dismay over a particular attack, disgust with an Israeli policy, support for Palestinian statehood or opposition to a statement made by an Israeli in 140 characters without blood libels, gloating about Israeli kids going missing or rants about a concept of 'Zionism' that owe more to the 'Protocols' than reality. Indeed enforced brevity would tend to lead one towards not including that sort of extraneous anti-Semitic sentiment.
Sure, Twitter is an utterly terrible medium for making carefully reasoned arguments about how to reconcile conflicts and redress grievances, but on the other hand it's a fantastic medium to rant and have the "I was misinterpreted" defence if anyone ever suggests your abusiveness towards the other side of the debate goes too far. Academics are certainly not immune to enjoying a rant about their enemies.
It's not exactly as if Israel and its actions are seldom criticised on campuses, or indeed on academics' Twitter accounts.