I'm sure with an Israeli and an Indian on board, that wouldn't have been allowed. Of course it would, we wouldn't want to profile now would we? If we have to nearly strip search old women with walkers and WW-II era Medal of Honor winners, but let those of Arab or other Middle Eastern descent walk right on board, unless they come up on the "random" draw, we could certainly have some "sleepers" working on the shuttle. Not saying that we did nor that this was terrorist sabotage, but I am saying it's way too early to rule that or much of anything else, out.
It would have to be a terrorist inside NASA ---it seems that everyone would have been very carefully screened and no Middle Easterners or sympathizers would still be working in NASA where they'd have that kind of access. I can see an accident be the more likely explanation. A couple hours before, I happened to be looking out the window and saw a pretty large meteor ---it seems something like that could hit a space shuttle and damage it enough. But nothing should be ruled out yet.