Terry gets the financial benefits of being the 5th (touring) member of U2, but he also is able to walk down a busy street in broad daylight and have nobody recognize him, or bother him. I'd say he's got a pretty good gig. Obviously he doesn't make as much as the other 4, but I'm sure he gets paid well.
For all of his contributions, I'd find it a huge respect to allow him a moment to be announced during the band intros when Bono does his thing on the mic.
Would be great for him personally to be on stage. Plus it would help with us determining what's the human element to their live sound vs the programmed loops. I'd like to be able to see what parts he's playing.
He is obviously loyal to U2, they being his employer. He's never going to say he wants to be on stage since it might cause friction. It'd certainly give the media a chance to muck rake. So I attach no relevance to what he says he wants.