The theory that the police are investigating has been around for a long time and is not mine. No idea who published it first.
But it wouldn't be stupid of the police, because Riona is probably the weakest link in the chain and could be turned over. Maybe someone also observed the MC giving money to Riona in EP5.
Lily is not out of the running for me as an undercover agent. It is a little strange though. Quinn and Vinny probably get their drugs from the same dealer. So how is it that Quinn is selling her drugs cheaper than Vinny? And you have to remember that Tommy can't afford Quinn's drugs, but he buys from the expensive Vinny. It's funny. Unless Lily can sell the drugs so cheaply among the Pink Rose Girls because Lily has to maintain her cover undercover.
But why is Lily investigating the Pink Rose. The secret word is Golden. I assume that rich guys are being ripped off in the Pink Rose. Maybe Stephen is one of them.

Speculation.
Is Tybalt maybe the son of the Madame and was foisted on Stephen as a son? Wow, it's giving me the creeps.