This is only your opinion. There is a reason why doors have lighted exit signs and why there are so many. You cannot under any circumstance block a fire exit. There must be a clear and direct path to the exit. Because the school put you there does not mean you cannot be held liable for someone getting hurt trying to exit through that door. Be very careful listening to such people.Actually I was placed there by the school. There were 7 other exits in the building that were completely unobstructed and all were double doors. Additionally there was a good 6 feet of space behind my system. If there was in fact a safety hazard, exiting the building would have been extremely easy especially since there were 4 other exits on the same glass wall I was on.
I've been teaching fire safety for over 20 years now. I teach by NFPA standards and common sense. Think of this, picture the lights going out and everything black. The only thing you can see is a lighted exit sign. You head directly toward it only to trip into a light stand, speaker, etc. In the mass confusion you head for the first exit sign you see but you can't get out because you just tripped over equpiment. It's to dark to know you might have gone around it. People are taught to follow the lighted exit signs that's why there cannot be any obstructions in the direct path to that sign/door/exit.
Also, it is not your judgment to determine whether there are enough exits in the room. The exits are all there for a reason and no one is given the choice to block the ones they see fit. Sorry but that's just the facts and the law. What you choose to do with those facts as a professional is up to you. What I would suggest is to ask your insurance liability company if it's OK to block a fire exit with your equipment just because the school or venue says so. After all they are the ones who will be protecting you when someone gets hurt or dies.
I'm just trying to help you here, not lecture you. Take this as a learning experience. What you do with it is up to you. I speak from experience, fact, and the law. Maybe this will help.
Lookup section 10.17 and go to places of assembly. Although this is for the State of Massachusetts I doubt very much that your state will be different. Many of these codes are written from NFPA standards as well as others.
http://www.mass.gov/Eeops/docs/dfs/osfm/cmr/cmr_secured/527010.pdf