I don't really get why these people are so mad at Uber not joining a protest. I'd guess they were mostly mad for other reasons Uber gets attacked.
I'm just not sure what a taxi protest achieves. In practice the protesters and distressed relatives probably need to get to the airport and back in the emergency circumstances. Boycotting political buildings would be more understandable.
It applies pressure on a powerful, popular and perhaps a bit fragile US company.
Which in turn, the protesters probably think will apply pressure on the government ro change it's policy.
Reading the messages these people left while deleting the app I don't believe your reasoning applies.
This is not a protest it's called "rage quitting". It would be interesting to see the actual numbers and reactivations when the need a ride.