A couple of points -
1. There is no "NCAA-wide transfer rule." Each sport gets to decide how they want to handle transfers. Per
this article only D-1 baseball, basketball, football, and men’s ice hockey make you sit out the year.
2. I'd say over 90% of the players in the transfer portal are graduate transfers, I would hope few folks would have a problem with their being allowed to play immediately. The waiver situation has gone crazy and I no longer understand the criteria.
If a regular transfer hasn't been redshirted, they can give up the redshirt as the year they sit out and not lose eligiblity.
3. Those are club endeavors not under NCAA jurisdiction, so they "don't count", even though Equestrian is a varsity sport at some schools (to build up their Title IX numbers). I'd like to see athletes be allowed to transfer and play immediately if the coach leaves, as well as when a school is put on probation.