Does it matter if they are truly moral or truly cynical but think they can capture some sort of "morality premium" by taking a stance?

Yes they are beholden to investors. But so is Musk. The thing is that his investors are also his fans, so a majority of them will approve whatever tactics or schemes he comes up with.

Anthropic may be able to cultivate investors in a similar way, without even trying. After all, why would you invest in a company if you didn't agree with how it was run? Of course there could be a hostile takeover by private equity group who thinks they can squeeze more value out of the tech, but that is harder the larger the company grows.

Edit: also, the morality premium is usually enjoyed more in terms of employees than investors. Google for a long time attracted idealists, by which I mean they were able to pay slightly below market rate for a certain kind of person. If you have a moral compass and you get an equal offer from oai and anthropic right now, which one you choosing?