Both can be true. The story is entirely plausible, though. People had cell-phones and the towers had already been hit.

I think there's a cultural memory hole thing going on - Hijackings used to be really, really common and were usually resolved without too much violence. Being hijacked would definitely ruin your day, but the general wisdom was to just sit tight and wait to be rescued or ransomed or whatever. A lot of the time passengers would be released after the hijacker's demands were met.

Pretty much the only reason 9/11 worked as well as it did is because up until then no one had tried it. Once the people on 93 knew what the stakes were it was, what, 150? 200 people against four or five armed with small knives? Most people aren't fighters but those are still really, really bad odds.