He didn’t steal it. He took it down from a place where it was being inappropriately flown, and turned it in at a reasonable place (the ROTC building).
That doesn’t appear to be stealing, in my book.
The other way to look at this is one more degree of heat on the CW meter. This is not a narrow, legal issue. It's a burning issue of nationalism and who owns the Southwest. In ten year, guns will be drawn over such events as the "wrong" flag being taken down or put up.
It's a mile marker on the road to CW2: "Back in 2007, people got angry but didn't shoot each other.....yet."