So - PLB's are required by customers (oil companies) for all passengers in Canada, the North Sea, and by BHP in Australia. There is the common thread. Its a customer requirement and you can bet they pay for them.
The reason that PHI and Bristow are fighting the proposed state law is simple and unfortunately overlooked in the thread. It's not being fought because its not a good idea, it is - it's being fought because of the legal precedent that it would set. Allowing states to set regulations for aircraft operating in their states would be a nightmare. For example - lets say you are in your 76 flying out of Texas and when you get offshore the customer tells you he needs to send a man in to a base in Louisiana. Do you refuse? Do you risk being stopped by a state inspector upon landing in Louisiana and not having the state mandated widget? We're talking PLB's not widgets - you say. One thing that is universal. Give a government entity power over one thing and soon its tenticles will grow.
Another example - since the law would mandate PLB's for persons flying offshore from Louisiana, would that require airlines who fly from New Orleans to say Cancun Mexico have a PLB for all passengers? The scenarios are endless.
Anyway. Having local governments set aviation regulations is not the answer. Its all on the oil companies. If they want it - its will be done.