I remember there being something that said that Urizen was using the Qliphoth as a sort of life support since he was suffering to the same decay that V's body was, but I can't for the life of me find it. Do you have any idea where this info might come from?
Because you said "life support" that made me think about Dante when he was defeated by Urizen and stayed in a coma for a month.
The Qliphoth acted as a life support for him during that time because the DMC5 guidebook specifies that the Qliphoth couldn't distinguish between Urizen (Vergil) and Dante.
Mistaking Urizen, the demon king for Dante who was injured, the tree supplied him with power during that time.
In comparison to V who had little demonic energy left, I don't think Urizen was suffering that much from decay because the Qliphoth must have provided him with energy from human blood that was used to grow the fruit.
So yeah, I hope this helped!