I figure Gwynn is a Zappa fan. :D

https://www.youtube.com/watch?v=-lkJ3hxRsUg

It's uncertain whether Ozzid would want to help Gwynn. He never seemed interested in destroying the world, and came to demon-meets only because he was too weak to resist. On the other hand he may feel some degree of kinship with other demons, and might not like a person who imprisons demons. But if Siphy were released and restored to a mostly sane state, then Ozzid's bond would be in effect and she could give him orders.

Let's not forget his kinship with Kiki. The ferret might have vouched for him already.

Ozzid seems pretty weak-willed, which is why Quint was able to control him and create the bond with his kin in the first place. I have no doubt Gwynn could do the same without much trouble.