NAM is open source. Who’s to say Line 6 didn’t just take the source code, and customize it so that it neatly works with the Stadium for the capture process, goes to Line 6 servers for processing, and out comes a chewy capture for the Stadium?
It largely removes the problems with the capture process, making it about as easy as a Kemper, while sounding far better.
EDIT
Looks like Steve also used the MIT license, so it doesn’t require Line 6 (hypothetically) to submit their changes to the software, only to include the original copyright.