I have also heard people's accounts of the fish being weak in general. Also that they live less long than the same regular version fish. I haven't ever kept the Glo-fish.
Maybe some real life keepers can share their experience. On longevity.
If the real person accounts are notable, then a conversation with the kids about the possibility that Pinkie and their friends might not live as long as a different choice, might allow them to make a different choice.
If those are the fish you (or kids) prefer, then select only fish from a healthy active tank, no ill or "iffy" looking fish. That will help you have a better possible start.
These are not injected with dye, or tattooed which those fish for sure have been handled and treated in a way which usually shortens their life significantly. These are genetically modified so they are naturally the color they are..
AND, please note that the usual fish which these Glo-fish are, most need to be in a group of their same kind to live their best life. Not one of each body shape in the rainbow of colors. Not having a group to hang out with stresses them out a great deal. Except for the Shark and Betta.
There are Tiger Barbs and I think also Cherry Barbs, Dannios, Albino Rainbow sharks, not really suitable for a smaller tank, and the Long and shortfin Tetras - Gymnocorymbus ternetzi aka Blackskirt or Black Widow Tetras which can combine to make a group, though they might still hang out with the short or long fin versions more often.