As I see it there are two schools of thought on rebreather training:I'm the OP so not a rebreather diver at all, but it strikes me the requirement for T1 comes from a more conservative philosophical approach on OC vs CC usage. Until recently T2 was required before CCR1.
1. You need to have sufficient OC training and deco experience to deal with bail out situations (GUE fits in this school);
2. You need to understand what you're doing diving a rebreather and train specifically for bail out during rebreather training.
As I see it the nr. 2 school has an more academic than empiric approach. I'am not sure which school is better. Maybe it's just a matter of doing what works for you?
GUE is conservative in many ways. Their base is doubles setup, the rest (i.e. rebreather, sidemount, etc.) if you need the tool for the job in their opinion. Everything they do is derived from doubles standard. Beacause of that they are less flexible than other training agencies when i t comes to rebreathers (and sidemount). Besides that, they seem to have quite some reservation to rebreathers in general. Knowing their history and the dives they did it's understandable.