No, they're kicking him out because the public is coming to see it as a moral imperative that Uber needs to be held accountable in some way for their behavior. I don't really care if the investors have or follow their morals, as long as they are in some way strongly incentivized to behave in that manner. We can't make the people have morals, but we can strongly encourage them to act like they do.
The investors could have gotten away with much less, certainly without firing him, from a PR angle. I say this as someone who hates Uber with a passion because of the senior management's sliminess, and who no longer uses Uber because of it.
My guess is that there are also much deeper issues here. And things like the Waymo deal indicate that there may be a whole slew of other slimy behavior that will end up hurting Uber more in the end. My guess is that we don't know the depths of poor decisions at Uber.
Don't kid yourself into thinking that a majority of the public knows or even cares about the things that Uber has done. They use Uber because everyone else uses Uber and to take an "Uber" is to use a "Kleenex" or to "Google" something.
Firstly, I will continue to kid myself. Investors are humans, my friend. Everyone is capable, and should be expected, to put decency above money when the two come into conflict.
Secondly, it doesn't matter. Many people cared about the morality, and it was enough to make a difference.