Eh c'mon Kochou, surely the fact that she's eating a hamburger and not a people-burger should be enough proof she's not a minion of Muzan.

Frieren at least seems to be considering the apparent biological differences from her local variety of demon.

The real issue is those three are getting jumped by everyone who cares about Soukaku (basically all of Section 6, so almost certainly Miyabi), and the jumping gets literally 10x worse if they hurt Wise when he inevitably tries to talk them down and protect her!