Now I have to say that I would not be beyond attending another school's Spring Practice, especially an SEC school's, for no other reason than than to do a little scouting for my own curiosity. And youyr bottom dollar is safe bet that I would be donning the Crimson. However, I would be all business about it (i.e. take my seat, watch the practice, and be friendly to those who are friendly to me.) There is nothing wrong or illegal about that. Frankly, that spirit is why the SEC it king.
Now parading around around in your school's colors being a jerk, that should get you ejected at the request of your own school.