No they can't shut off people since modem-laptop is peer to peer. Globalstar can only shut off people if they are using hotspots, if they are really the middle man between the user and the internet. But then they have to build millions and millions of hotspots, if possible at all since the FCC will only allow them to broadcast at low power.
The company is very, very vague about the business model for TLPS. So I suppose there isn't one. The FCC license is for low power, so that will be for communications between modems and laptops/smartphones. I don't see how Globalstar can enforce payment when someone uses TLPS between his modem and smartphone.