It also doesn't speak well to Uber's reputation that I have no problems whatsoever believing that this might be happening. Compared to all the other unethical stuff that they've done (such as Greyball), I can totally believe that they'd do this as well.

If it's possible for both the rider and driver to see the forecasted route at the time of hailing, it should be pretty simple to throw together evidence to show that different pathfinding is in use.

I celebrate his entire catalog.

Reading what they actually did (or accused of doing, technically), it's not shady at all.