I actually read the instructions for probably the first time ever. It is aquarium safe, but only after curing which apparently takes between 45 minutes and two hours. I does say: "Do not use on marble. limestone. brass, copper, magnesium, iron, zinc, or galvanized metal." Then there is a sort of sentence fragment: "Hard to bond plastics such as PE, PP, PTFE, PMMA, PC, or PVC." I think they meant to say something about it not sticking very well to those.
It seems to me that applied thinly or in small quantities it's probably fine and any damage it's going to do would happen during the first hour or so while it's curing. No, it would not make good potting compound.