Is the Boycott of the University of Illinois Illiberal?

I’m hearing whispers that some liberal-ish academics think the boycott of UIUC is illiberal and censorious. So let me get this straight. Is the underlying idea that, as an academic, you’re obligated to accept every single speaking invitation you receive? (Let’s recall the terms of the boycott: simply that we will refuse to accept an invitation to speak, or otherwise participate in an event, at the UIUC, until Steven Salaita is reinstated.) Or is it that you’re allowed to say no if your reasons are strictly careerist—i.e., the institution is not high-prestige or the honorarium too low—but not if your reasons are moral principles? Or is it that you think careerism is not only a moral principle but the only acceptable moral principle that would justify a refusal of an invitation? Or is all this liberalism talk besides the point, and it’s just Israel Israel Israel?