EVEN if they don't agree with those decisions, it's expected that they'll be a team player and provide support in whatever way possible. Up to certain limits,

EVEN if they don't agree with those decisions, it's expected that they'll be a team player and provide support in whatever way possible. Up to certain limits, and respecting certain ethical norms. Apparently the Kapors came to the conclusion that those limits had been reached, and that Uber's behavior ultimately failed to meet those norms. Or in their own words: "We are speaking up now because we are disappointed and frustrated; we feel we have hit a dead end in trying to influence the company quietly from the inside." And so they felt it was time to act by other means.