This is just another version of UV-curable resin which shows up in those As-seen-on-TV commercials.
As their website https://www.5secondfix.com/
states "Not a Glue! Super Powered Liquid Plastic Welding Compound". We'll have to see how well the Delrin bond holds in the long run.
Another one is BONDIC ( http://notaglue.com/
) and as the website name spells it is not a glue, but it works somewhat like glue (check the FAQ section). I just got a tube in the summer (at a Target store) and I have used few time. I can see that it will be useful in my hobbies (if not for anything else, for gluing clear model parts and for making headlight lenses or maybe even car windows).
Nsbob, how does the glue joint look? Is it a blob of glue around the handrail, or is it barely visible? Can you take a closeup photo and post it here?