Nice find!
I've taken my two ebikes to the Grand Canyon on the south side of the rim and had a blast back in 2016. We were able to explore more of the canon and take pictures without +250 tourist in the background. We probably put +50 miles on our ebikes in a few days. The Grand Canyon had dedicated walking/bike paths in certain spots and traffic wasn't too bad for the share the road spots. Very (e)bike friendly place to visit.
I didn't take my ebikes; but, the Utah parks in Canyonlands and Moab are not (e)bike friendly at all. Very narrow paved roads, zero shoulder, a ton of people weaving in the lanes sight seeing and not paying attention with oversize vehicle and campers, and distances between attractions to put any battery ebike to the test. You would have to ride in the regular lane holding up traffic most of the time until you can find a place to pull over. I can see places like those for if you want to camp or explore off the beaten path with an ebike. Unfortunately, those roads are unpaved and 4X4 and smaller off road vehicles are usually speeding in those places at 35-70 mph.
Some parks might need to improve the trails and paths for bikes also.