I think you can find some sort of "abandonment" in any situation (sickness, monetary deficiencies, legal matters, etc) from family, sorority/fraternity, church members, friends, etc.
So, it should not be too surprising in this instance. It is unfortunate that this has happened, but if you and others are there for him, and are there for him GENUINELY, then that's all that matters. You cannot worry what others are or are NOT doing, frat brother, soror, momma, daddy, sister, brother,son, daughter, grandma, grandpa, friend, whomever. They will be held accountable for their actions.