Possibly, but it's worth remembering that the lines on the training page are only fits to the data that we have from the crowdsourcing project. So, I agree that the single position passing curves that show increasing training with height are unusual. But there are relatively few tall guys getting consistent passing training. And you're definitely correct, their training speed is very likely to be boosted by a elastic/CT effect.
On the other hand, the two most popular training types ever are pressure and 1v1 forwards. In both of those it's apparent that the training v. height slope is dependent on the training type, not the skill itself:
-for pressure, the inside defense secondary is slower the taller you get.
-for 1v1f, the IS secondary is slower the taller you get
-for 1v1f, the JS secondary is faster the taller you get