This isn't true, it is not exclusive to the ISM bands. You can run it on any band you choose so long as you have a license to do so. Case in point: the ham bands
I've got a ham license so not a big deal for me but for those wanting to try radios without a huge investment a pair of $20 Lora AT serial radios are a great way to dip into digital radio.
So before using something that was designed depending on some non-ham part of the regulations for its legality, such as part 18 (ISM) in the US, on a ham band I'd want to look into the details and make sure it is not doing something under that part but not allowed under the ham regulations.
It's a procedural thing. The FCC will tell you did it & tell you the penalties. Your options are zero.
Repeaters may use any method to limit access and control to authorized users.