No way. Your son is in college now, likely an adult (or almost an adult), and starting an independent life where he will need to learn to stand on his own two feet and not have mommy/daddy/other parent/guardian swoop in to save him whenever he faces a challenge. And I guarantee if you do try to get involved, that entire frat will be like, damn, that was a good call not to accept him, otherwise we would have had his mommy/daddy/other parent or guardian all up in our business for the next four years.
I am really sorry this happened to him. I know this kind of rejection hurts and I know when your kid is hurting you want to do whatever you can to make it better. So be supportive of your son. Reassure him, love him, listen to him. But under no circumstances do not get directly involved. He’s not in kindergarten anymore. You will only make it worse.