This is actually not true. Its 3 hours a week and if the school didn't use the whole 3 hours then the coach can coach. Most don't because they want to save their hours of they've used them. Any coach that was coaching had it approved by their AD and the head of IAMM. Carry on and find something else to complain about.
Also, if its agains the rules, do you think a coach would be doing it openly in front of all their fellow coaches?
I'm surprised more coaches don't plan around if they know this tournament is going on so they can coach. Why not?
I can only make a conjecture... if you have all returning seniors, who are possibly free lancing, maybe its more valuable to use those hours differently. Maybe it's more helpful to just observe if they have a trusted assistant. I would guess if the coach is opting to coach, maybe they have a younger team and want to be a bit more involved early on, or they have a large number of 2 or 3 sport athletes, they don't use all 3 hours because they're in season- and its one of their first times together. Probably different reasons for different programs.