Aaarrrgh! I didn't even think of that! Yes, if he keeps trying, he can simply use his divine intervention! It says that any cleric spell or domain spell would be appropriate. He's above 10th level, so he has the feature. It's perfect. As long as you could justify him being conscious at 0 Int, he would be begging his dirty for help and his deity would very likely just intervene with a greater restoration.
Personally, I would not let somebody with Int 0 call for divine aid. He cannot even remember his name, let alone his gods. He is a high level guy though, his deity might wonder why he has not prayed for a while. It would come down to whether the PC RPed well or not. Is he a high priest of a church? Is he devout and always prays at sun up and sun down? If so, then the deity has an X% chance of noticing that he has not done so and might turn some attention to the problem at hand. An un-asked-for Divine Intervention. Same rules, just a different manifestation.
If they guy is just a different type of wizard in plate who never RPs his piety, then I would not have his god notice or intervene.