Many coaches recruit portal transfers, not always just for their skill, but for experience and leadership.
Could it be a possibility that they just didn't see that happening and just as a player has reasons to walk away, the coach has his reasons to let players go. Or perhaps your son jumped on the opportunity before doing homework on his current situation.
I am sorry that this has happened to your son.
If a player is on scholarship, it cannot be taken away. However, at this time it does appear that he should not consider transfering to another D1 bb program.
In the college baseball world, there isn't a huge need for a lot of lefty pitchers on staff unless they get players out.
The most important thing for him is to graduate and move forward.
And you do as well.