Fire sprinkler heads normally cover 100 square-foot areas and any fire in an enclosed area will cause a curtain of heat to rise up the walls along the ceiling and trigger the head before the temperature in the room rises 15 degrees overall.
Even if one took a cutting-torch directly to the tank while in the room the sprinkler would go off and drown the silly-ass trying such a stunt long before he could heat the tank to raise the pressure to a critical point.
An 80 degreeF temperature change on a car tire will only result in a 5PSI change.
If what you suggest would be a concern, a simple 16gauge metal cabinet around the assembly would shield quite effectively.
A 2,000PSI tank can do an awful lot of damage if it explodes. On the other hand, I wouldn't see any problem with putting a safety valve on the thing; such a valve would certainly be required on a CO2 tank, but should probably be used on an air tank as well.