Not sure what a low grade felony is, but I am on the understanding it is legal to record without permission, but cold you direct me whee you got your view please?
Sadly, Mr. Kashuv needs to do what everyone should do when asked to be interviewed by the police - say nothing other than "I don't answer questions without the advice of counsel, if you want to arrange a meeting I'll retain counsel and you can speak with him or her." And then "Am I free to go now?" And then if they don't say yes don't say anything but politely identify yourself and provide an ID if asked.
Mr. Kashuv should retain counsel for specific advice, and perhaps the next time the school singles him out he should call his attorney before or while anyone from the school is trying to talk to him.
Florida is a two party state, meaning Florida law says that both parties need to consent to recording of conversations.
But, there is a fair amount of First Amendment law saying you have the right to record conversations with government officials acting during their public duties.
https://www.jacksonvillecriminallawyerblog.com/2016/03/it_is_illegal_in_florida_to_au.html
The deputies might claim that their conversation was not public.