Hmmm...
"Even with the removal of all the bottles and the eye-watering halon disposal fee"
I can't remember - was the 'Halon system' ever tested? I can see a Swiss solution here (or possibly Cayman Islands). A convenient 'engineer', and even more convenient 'legally required examination', an eye-watering never-installed-halon installation fee, eye watering never-needed-to-dispose-of disposal fee - and now the fee for the never-installed nitrogen room. That's an interesting retirement fund for a room that can catch fire conveniently and have a convenient 'fire protection system failure' if it ever becomes necessary...