Beane should be strongly considered for the GM job.
If he is brought in, it's because McDermott knows him and feels comfortable with him going forward. The fact he once played QB should be beneficial as he knows or should know what offensive talent looks like.
Being an NFL GM is akin to being the top scout of college players, scouting players on other teams practice squads and scouting free agents.
Beane would make sense for the job.