Yeah but why get rid of quinn in this case? If they take over buddy anyway, quinn would just be working for them afterwards which would be money for them.Vinny is an ambitious guy, and he wants to rise higher.
If Mick has worked with Buddy for a long time, he probably knows the main suppliers, and will be able to work without Buddy. Therefore, getting rid of Buddy would be a natural desire for these two.
Mick and Vinny are useful to each other, and Buddy becomes an excess.
If they are afraid quinns gonna rat them out, they have to kill her anyway, capturing rio doesnt really helps for that, they should have captured quinn in this case.