I think philosophically there can be IG with contact, but that comes down to judgement. For instance if the QB doesn’t see the contact coming and it affects his throw, i would likely pass on the IG. If there is contact prior to the pass, for instance the defender has began to tackle the QB and he chucks it, there better be an eligible i the vicinity or he is outside the free blocking zone and the ball makes it to the LOS. Point is I think touching by B negates IG, but contact does not always negate, but it could.