I expect almost ALL of Malaysia Air's pilots and cabin crew are Muslim, and have been for decades; the Egypt Air thing never was clear as to whether it was a suicidal guy in the cockpit (And the theory on that was suicidal, not jihadi) or whether things were going to shit and he was just praying for all he was worth.
Terrorism looks like a very strong possibility, though. The stolen passports are pretty suspicious and may very well indicate terrorism, but it's just as possible that it was terrorism but unrelated to those particular passports. I'm pretty sure that in that corner of the world it's not difficult to find a few people on almost any given airliner who are traveling on stolen passports and fake identities...SE Asia and China are rife with criminal networks and identity theft, after all.