That's exactly why you pay for the service. SiriusXM put the satellites into orbit & are now getting back what they spent. The LTP's had free internet radio BEFORE the app was even made, that's what the initial terms were. It more than likely didn't say; " if there are developments such as an app for a mobile device, you will be able to listen to that whenever it is finished."
Lifetimers didn't pay to be able to use the app, because it didn't exist. Therefore, if they want it, they pay for it.