"New" is relative, but Ben Shipps has owned JB's for two or three years now and he was an instructor there well before that. (He's the son-in-law of the previous owner, who is Jack Brown's son). The altitude change has been more recent, as I understand it. My friend wants to speak with Ben about the altitude, but obviously this isn't a good time.
The altimeter setting might be a contributor. I suspect JB's wants patterns to be flown at 500' above the water, so they zero the altimeter and just use 500'. This puts them 140' or so higher than MSL altitude. Extra altitude for the seaplane combined with a pattern descent for the Warrior may have combined to put them at the same altitude.
In the NTSB press conference, the lady representing the NTSB mentioned that they had interviewed personnel from Polk State and from KGIF, but she did NOT say whether they had interviewed anyone from JB's. I would not be surprised to learn that lawyers have told JB's not to make a statement, but of course I don't know that.