This decision somewhat clarified the Fair Use doctrine, but it's still a very gray area. In this case, Burbank used a 20 second clip of a 4+ minute song in a medley. The band version of that would be quoting a short excerpt of a larger piece in a medley, which you could now argue as fair use based on this decision. The way I read it, that would not cover you if you take an entire piece of music, or even an excerpt if you aren't making a medley, and arrange it for your band as "fair use."
However, I'm not the one you need to convince. If you want to volunteer to be the test case, you can go convince a judge.