I think you might overstate the case. The US authorities obviously have a line of enquiry to follow in Florida, and the obvious people to ask are the permanent staff of those schools. As each school must have a record of all its students, and if the FBI wants to talk to any contemporary students, they'll know where to find you.
If you have information which you think may be of use to the FBI or NTSB, you should volunteer it straight to those authorities. I don't want this forum to become a place where amateur sleuths compare notes as to which schools were hosting 'suspicious-looking' students. You've either got useful info to give to the feds, or you haven't. Don't speculate here please.