I bought a bottle of Tight'n'Up and used it on a print done on Breathing Color Chromata White canvas on my Z3100.
The bottle must have been old, since it had no warning on it about inkjets. After seeing this thread I contacted the manufacturer and got this reply:
"If the ink(s) on your giclee didn't run immediately, then you're probably fine. We don't recommend Tight'n'Up for use on giclee prints because we don't know if people are using solvent-based inks or water-based inks (these are the inks that can run, but not always). Most of the time, Tight'n'Up works just fine on giclees because there is a gesso barrier that separates the Tight'n'Up from the ink. However, we cannot guarantee that our product will work 100% of the time on giclees."
I used it sparingly along the top and bottom of my canvas and it worked fine with no damage visible.