"You cannot criticize X if you you do not criticize Y and Z (where I get to rank X,Y,Z in order of badness)." Hawking is simply declining to appear at a conference hosted by Peres, a man who was an architect of the West Bank settlement enterprise. You can call this a 'boycott', but he's just declining an invitation because of unhappiness with his hosts. Lots of Israeli and Jewish institutions boycott people they don't agree with. In fact, they do more, doing their best to stifle dissent and prevent their opponents from speaking (see Finkelstein tenure fight, or Tony Judt's travails). All that Hawking did is decline an invitation. Stop whining, Carl.
Report: IDF find M-16 rifle hidden in Palestinian's car in West Bank (Haaretz)
from the article: Hypocrisy and double standard: An open letter to Stephen Hawking