Interesting, have never experienced that one. The qualification (train the trainer course) was the same, except the additional base training for the TRI of course, same for SFE and TRE. Well, you live and learn.
Found it in FCL, it is labelled as "restricted TRI", therefore of course the above quote is still correct, any unrestricted TRI should be able to extend the 90 days to 120 days.