Would it be frowned upon that with a uncommanded nose up, the pilots just do a full loop?
No airliners aren't stressed for loop maneuvers.  The proper action for that kind of extreme pitch attitude is to roll 90 degrees and let the nose fall, then roll level as the horizon is passing.  Of course if you had a nose up stab trim runaway that left you stuck with that pitch tendency (effectively a much lower trim speed), you're back to square one.  

You have to slow down to as close as you can get to the trim speed that the nose-up-stuck stab wants to fly at.  You might find that you have enough elevator authority to maintain a level pitch attitude if you get the speed down to a minimum flaps up speed, say 180kt.  

Then you can do other things to create a nose down pitching moment, like dropping the gear, and on most airplanes, extending flaps.  That should be enough to remove most or even all of the elevator input required depending on where the stab was when you killed its runaway.  In an extreme case where you've run out of options, you might even try getting passengers to move forward.

In recurrent sim training, a nose up stab runaway was always a more pleasant exercise than a nose down one.  Mostly because slowing down, and gear and flaps helped, and to the extent you had to hold continuous nose down elevator, one of you could brace your knee against the column to help with most of the push force and it was easier to hold it for extended periods.  A nose down stab runway was a much more difficult situation.