Actually a question just as important, if not more so, is did MB itself condemn the act, publically distancing themselves from the actions of a completely indep group, with a different philosophy
The Muslim Brotherhood is under no obligation to condemn actions it is not responsible for, just as you are under no obligation to condemn the actions of a few at Abu Ghraib wearing the uniform of your country.
The soldiers of Abu Ghraib are not an "offshoot" of me. If they were, I'd have reacted the same as the Military, the actual organization the soldiers were an offshoot of, did....condemn their actions, and make it clear they were not part of any sanctioned policy.
So yea, under the current circumstances being discussed, they absolutely had an obligation to condemn actions of those that were assocated with their organization. Otherwise the perception is that of tacit support/agreement, if not actual sanctioning