That is not correct. It is not easy, it is very difficult in fact, to come to the realization that there is an underlying medical reason for subtle personality changes.
If it is a 'personality issue', and not secondary to any medical cause, then the best course of action, if you wanted to actually help the person, is a combination of real life consequences, such as being forced out of Tesla, perhaps on a leave of absence, and psychotherapy.
It IS most definitely our problem. No, you can't force him to undergo a medical exam, but leaving things as they are is cruel to him, unfair to us and unfortunate for the future of the planet.