Investors don't lose their right to an opinion. If anything, their opinion matters more because they've put their money on the line. Since it appears Uber only made token attempts to hear their feedback through past crises, it is entirely appropriate to take concerns public now.

Founders don't get unconditional support from investors. They aren't therapists or doctors or lawyers. When you take money from someone, you're giving them a promise in return. Yes financial gains are part of that promise, but so is conducting yourself ethically and ensuring that the "business" is just as successful as the "product". Treating your people right is part of the contract.