I saw the same group of people hanging out at Greatfull Dead rock.  When I got to them they were throwing fire crackers.  Then they started throwing them at us so we got the hell out of there.  As long as they were not throwing crap at you, I would tell them about the dangers (foot entrapment and flush drowning) and then let them be.  If they did get into trouble, I would absolutly try to help... from the shore.  Throw them anything you can find or try to reach them with a stick.  What is our tally of deaths so far this year?  I heard we were atleast up to 6 so far.  I know it's harsh, but just think of it as natural selection.

Peace, Eli