There seems to be some confusion here, a player can transfer but just not to another D1 program.
However, there is a belief that players should have a right to do so, but IMO only if the player is asked to leave. But then my opinion is that he is probably asking the player for a reason, not just because he wants to. And its based on production. I remember the outrage years ago when Kevin O'Sullivan let a player go who had 2 redshirt years and never played his 3rd year. This was just when the new roster and transfer rules would be coming into effect. He helped the player find a more suitable program without penalty. Meanwhile, its apparent in his case that he understands how to build a winning program and thats by recruiting 35 players who will all contribute in one way or another.
I am not aware of D1 coaches who turn over complete rosters, I believe that this is an exaggeration. I am aware of coaches who will make adjustments by cleaning house of players that have been kept on rosters who probably didnt belong there in the first place. This is a harsh reality but college baseball is a business. I do believe that most really good new incoming coaches believe that the players are innocent bystanders and unless you can support your accusations, go ahead. And unfortunetly coaches do abuse young arms. But I find folks dont care until injuries occur.
This was a very poor practice that was common many years ago, however coaches do have reputations to uphold. However, you better believe now that after the first year coaches will bring in lots of players to compete for roster spots, so be prepared.
Also, I dont believe any decent coach would tell any player not to come to the program he would be leaving. I just think these comments come from someone who is frustrated that their player is not in a place he thinks he should be.