If he still believes what he saw was real then he's not fully recovered yet which is probably why he's refusing the meds. There's something called insight which not everybody has while they are sick....Ie you don't always know you're sick. I'd say he needs to take them to get better and hopefully gain more insight. After that I'd say it was his choice. Chances of relapse without meds are really high, but given that it was stress based there is a better chance of long term recovery without meds if he stays on meds now.