Maybe he doesn't need medications, but could use a therapist? If he learned the anxiety by being away then it means he can learn to cope with the residue. Depression can be monitored this way and any worsening of symptoms could bring an informed psychiatrist into the picture.

I also think that drinking alcohol is fine if there is no prior intent to do it for some relief. Im on psychiatric meds and drink occasionally. Im not drinking to relieve any negative feelings I may have and have honestly talked to my doc about my consumption. She didn't say anything about him drinking all the time or any concerns that he was self-medicating.

Depression can happen to anyone. Its better to exhaust therapy before adding medication if the depression was situational in nature. Also, he can be one of the unlucky ones who experience serotonin withdrawal.