You are correct GT isn't a "big" job at the moment but a coach like Marshall could bring back the Bobby Cremins days.
Marshall is a Son of the South, and at 53 is the right age particularly when one factors in that guys like Roy Williams (age 65), Mike Krzyzewski (age 69), Jim Boehiem (age 71) and Jim Larranaga (age 66) will not be coaching forever and that The ACC could see a shift with the aforementioned retirements in the not too distant future.
Not saying he would take the job bus if I was The AD I would make it very difficult ($$$) for him to turn down.
GT has a lot to offer for the right guy.