What is riot's policy against intentional afking in ranked?.

why dont you try it and see how many it takes as a experiment?

The same as the policy about AFKing in any other game mode: it will be punished if done too often, on top of the low-priority queue that comes with it.

i understand that AFKing at all is consider a no no

Policy is B&

If your troll was to afk without flaming or telling on yourself in chat it's likely you would never be punished beyond the Leaver Buster system.

AFKs and laggers need to be punished worse than toxic people.

Leaverbuster will auto punish them. It does take consistent afk behavior though. I've done it a few times myself and haven't been punished, but only because it is very rare. If you do it regularly you will see punishment.

Porocles doesn't typically show up on PB&M at all, he's on Help & Support. I think you mean Tantram.

Not sure exactly, but I think that first time is low priority queue, then it starts moving into temporary bans.