There is about the be a press briefing, so more information soon.
It is not clear about the suicide belt that has been reported. If he has one, or has something that looks like one, then yes, hard questions for Egyptian airport security. But it remain possible that he is just making plausible threats.
One exiting passenger carried a letter from him, asking for a contact named (nfd) woman and that has led to reports that this is not jihadi or politically motivated action, and most reports say it has a domestic motivation.