Funny, I happened to read shu"t Beis halevi chelek 2:1 today where he is mechadesh that even though we pasken that a choshud to do one aveirah is not choshud to do other aveiros, if the action one is doing is a maaseh avaira one is choshud on everything.
He is coming to be meyashev the Rambam that a ganav who shechts the shchita is possul, cuz it is a cheilek of the maaseh Geneiva and therefore there is no chezkas kashrus.
Not sure how to tie this in exactly, but it fits somehow.