If you share your prejudiced views with a few close friends and the entire Twitterverse, where's the harm? It shouldn't cost you a job, should it?
What if you were in line for a prestigious position at, let's say, a prominent state university. You saw what happened in Ferguson, Missouri, and you tweeted about it. Except you said something about "Only #African-Americans can attempt to murder a policeman and insist that they are the victims. #WhiteFolks #WhiteFolksUnderAttack" because you're racist but it's your personal opinion. Would you then be surprised that the prestigious position evaporated before you could claim it?
Steven Salaita is unquestionably a supporter of Gaza, based on his tweets. He's also quite the anti-Semite, but that's his private affair as far as he is concerned. The University of Illinois had no right to pull the teaching post he thought was his until his tweeting exposed his less-than-acceptable prejudice.
The university fumbled around, searching for an excuse that would get them out from a problem of their own making. No one thought to fully vet Mr. Salaita before the job was offered to him, and when the tweets hit the fan, they were caught up in a controversy they had to get out of. A lot of their donors are of the Jewish persuasion, and a lot of their donors let the school administrators know just how unhappy they were with the possible hiring of an anti-Semite who would end up teaching other Jewish children.
Imagine the Imperial Wizard of the Ku Klux Klan teaching about past injustices done to the native American population. And teaching it to a classroom full of Ojibwa students. Would you really expect a thoroughly unbiased discussion, and would you really expect the students to say much in protest when their grade depends on pleasing the instructor?
But there are few jobs to be had in public academia these days, and especially in Illinois where the budget is so tight that the U of I gives preference to foreign students paying an inflated tuition. The school has the biggest population of Chinese students among all the public universities, who also aren't going to become major donors to the school after graduation. Keeping the donors happy is quite the priority.
Steven Salaita was told the job wasn't his after all, and the problem was his anti-Semitic tweeting. The administration made noise about civil discourse and the like, citing some of the tweets to better explain without having to be more explicit. It wouldn't be particularly civil to call Mr. Salaita a horse's ass or an arrogant prick, and those aren't causes to be cited publicly when denying a job. That's what gets said in private, while a candidate is being vetted. But they didn't do the vetting before offering.
Little wonder, then, that Steven Salaita is suing the university for exposing him. The lawsuit, however, is one of those legal actions that is meant to be settled out of court for a substantial sum of cash, which is all Mr. Salaita needs to tide him over until his tweets are forgotten and he can try to find another job somewhere else. There must be another prestigious institution in the US that doesn't have such powerful Jewish support.
Or he might try landing a job at a university in Gaza. He could do some good there, and he's a strong supporter. Well, maybe not so strong as all that.