I think that PVC terminal adapter is not listed for the purpose. Matter of fact, I'm surprised that the flex didn't just pull out of the glued fitting before the TA snapped at the pole.
A proper sealtight fitting should be used.
I believe the reason glue on adapters are NOT listed for sealtite is because you can't remove them. I know if you do a good job of gluing them on they won't come off, even with 80 PSI of water pressure and flexing. (RNC, LNFC feeding a hose bib on a floating dock for the U/V protection)
The spa guys use "spa flex" that is basically white sealtite for spa plumbing. They do use primer tho.
