Maybe he found one Gav..
I would not clearcoat a New or repro glass. I've been using Triple Thick for well over 10 years. I have a "test" Bally Bingo mini backglass that I cleared 9-10 years ago. It is not in a game. I check it every year for any sign of delamination, shrinkage, expansion etc - and it looks very good. BUT - There are no guarantees for the next 5 - 10 years. To seal an old original backglass with lifting etc - YES - you are arresting further lifting etc. It cannot really get any worse. To seal touch ups - YES.
But a new glass with #47 globes or LEDs behind it will last 20 - 40 years without any issues. I would not risk clearing a NEW or REPRO glass. If a customer requested I clear a new glass, I would have to write up a disclainer and have him sign it - I just would not risk it.