The fact that abandonment of a belief might result in one’s being expelled from one’s institution of education doesn’t mean that the position is indefeasible. Someone who starts doubting aspects of Darwinian biology might have similar fears about their status at their own institutions of learning. I don’t want to uphold the whole “Expelled” claim, but I think there is considerable pressure within many academic biology departments not to stray from Darwinism. Further, people in places like Talbot got positions at places like Talbot because their thinking led them to think that inerrancy was true to begin with. There have been people who have left their Christian academic institutions because they had doubts about the doctrinal commitments of the institution. And sometimes these institutional statements are given fairly liberal interpretations. If you apply at Calvin College the official statements affirm the Canons of Dordt, but I know that some people who teach there are not five-pointers (Plantinga, who taught classes there while at Notre Dame, openly said that the Canons of Dordt may not have gotten things right.)
Further, exactly what is built into inerrancy is a little complicated, and what it takes to be guilty of “denying the Bible” may have more to it than just rejecting some popular hyper-literal interpretation of Genesis. The medievals said “Authority has a nose of wax” and that is, I think, true of inerrancy, although there are occasions where you get explusions, or attempted explusions, from groups like the ETS. However, the attempt to get Open Theists out of the ETS failed a couple of years back. I take it you have read the Chicago Statement and know what the doctrine is actually thought to mean by its contemporary advocates.
There are stronger and weaker versions of MN, just as there are stronger and weaker versions of the commitment to inerrancy. It is a framework believe that the advocate will call into question only in the face of considerable evidential pressure.
One of the things I tried to explain in my long exchanges with the Calvinists was that someone might in fact believe that inerrancy is true, but at the same time hold, based on their moral understanding, that the Calvinistic conception of a reprobating God was morally unacceptable. They might think that the biblical evidence supported anti-Calvinism rather than Calvinism, and therefore accept both inerrancy and anti-Calvinism. However, if presented with sufficient evidence (based on Calvinist exegetical arguments) that inerrancy and anti-Calvinism could not be held simultaneously, they might choose, in the hypothetical situation, to give up inerrancy. It wouldn’t follow from that never really believed in inerrancy in the first place.
Even if Craig would believe in inerrancy regardless of whether there were strong evidence for it or not, it could be that he could say he was confident that there were lots of good arguments and reasons for being and inerrantist, or he could say that it was an article of faith. One's faith that something is true doesn't necessarily mean that you are going to make all sorts of ......stuff up to support one's beliefs.