Good idea he came up with—it’s nice that kids won’t have to worry about the fun going away because of a puncture. When I was a kid, my dad got tired of fixing punctures on my bike tires, so he bought me some “puncture proof” tires. Trouble is, they were not really tires at all—just hard plastic shells. Might as well have been riding on the rims! I think they lasted two days before I whined enough to get back to riding on air.
Probably before your time but before they invented inner tubes bike tires were solid rubber. The new “baloon” tires were an instant success as you can well imagine. I can just remember some bikes still having solid rubber tires but 99% of them had inner tubes.