Its solely based upon ivx. I would imagine he would at least put forth the idea to the team should we trust her, is this the best approach to get this job done. kinda akin to how he has done in xmen red.
I guess the question would be do you think the sheer number of times they have worked together should have occured considering their checkered past. I mean emma initially intended on killing ororo, switched out their bodies, attempted to manipulate and mind-wipe her, disrespected her numerous times including her marriage after it was annulled, and then most recently ivx where she straight up misled her. to call it a petty rivalry again is not looking at the whole in regards to his egregious her past transgressions have been to her.