It is not "rent-seeking, plain and simple". I speak from experience, as I've carried out many risk assessments against buildings for live events. Fire and building codes exist for a very specific reason: to save lives and prevent injury.
If you think being forced to install sprinklers is somehow 'rent-seeking' perhaps you should remember that the Rhode Island Station nightclub fire (in which 100 people died) could have had significantly less impact had sprinklers been installed (as the building code specified). There are too many examples to count of fires where lives have been lost as a result of inadequate prevention and control systems.
You may not like the fact that these systems cost money to install and maintain. You may not also like the fact that in most states that vast majority of commercial buildings require them. But they are very much not 'spurious' regulations.
Frankly i don't see where any of this outrage is coming from. They've already raised most of what they need from private donations. It seems unlikely they will actually be shut down. If they were somehow unable to raise the few tens of thousands more they needed to get up to code, it would be due to the greed and stinginess of the well-off so-called pro-business types in the bay area. If tech investors cared a fraction as much about promoting startups and the economy as a whole as getting equity and a solid return on their investment, fund-raising for this sort of thing would be ridiculously easy.
Alas most all wealthy individuals are stingy as hell; they might give you $100 if you kiss their feet and carve their name in stone. Otherwise go back to your ghetto and quit bothering them.