It's unknown if he's still mulling the trip over. If he does schedule a Muslim address it would certainly send a bad signal in this environment.
Democrats will say Obama has been unconditional in his support for Israel although his stance was questioned throughout the Democratic primary. Obama has gone to great lengths to make neutral statements about the conflict and has tolerated anti-Israel views from close advisors like Samantha Power and his former pastor Rev. Jeremiah Wright.
Conveniently enough, Obama is using the time before he takes office to stay quiet on the situation, which, shows respect for not sending out conflicting messages from the executive office. Some pro-Israel advocates want Obama to make a statement sooner than January 20th and are contrasting images of Obama's winter beach vacation with violence abroad to criticize the President-elect for not taking a stand.