I have GUE training and I am very much an advocate for GUE and believe in the philosophies (team diving). At the same time, I am not opposed to solo cave diving. Some times it's more convenient (aka you're not going to dive if you have to track down a buddy) or safer (I have had some bad experiences with cave diving "instabuddies") to solo dive. Although I believe in team diving, I also believe that I'm adult enough and experienced enough to do some solo dives on my own. I don't push depths, penetration, or deco when soloing and am exceptionally conservative.
My GUE instructors and friends who are GUE instructors know that I do those dives and don't hassle me over it. I know they don't agree with solo diving as much as I do, but they're not bitching at me and not reporting me to GUE police.
GUE is a training agency only. The "cult" people dislike are members who take things too far. That happens in side mount, back mount, different ccr brands. It's not exclusive to GUE. "GUE" isn't going to care if you go solo dive. Your instructor and your GUE dive buddies may not like it. But there's no DIR Detectives coming to beat on your door.