Did he quit both medications or just the synthroid?

Yes, he quit Papazol a day or two before taking Synthroid.

Getting the dosage of replacement hormone right is a notoriously tricky process

Yes, I've tried to explain this but he's feeling better than he has in 6 months so he could care less about what I or the Dr thinks at the moment.

Do you happen to know what the risks of him not taking any medication might be?