In reading several articles about this, the ruling seems to go against the spirit of why transfer rules were established in the first place. 2018's team has two kids that transferred in, and both just finished up their 30 days - that is fine, both kids changed schools within the same county - the decisions were sports related, and they sat out the 30 days without complaint.
In this case the kid transferred from an out of state sports factory at IMG back to his hometown to be with friends & family for his senior year. He absolutely changed residences from Florida to back home, but seemingly because his parents never went to Florida with him, he is being penalized for now coming back. Is it the letter of the law? Maybe. But the fact that he came back home from out of state is a legit transfer that involved a move. He wasn't just jumping to the school across the street to get more playing time.
The timing is also very suspicious. Reeks of a jealous parent or coach trying to get a leg up for a league or state title and trying to knock this player & team down a peg or two. To paraphrase Bad News Bears Breaking Training, "Let Him Play!".