Zuck May not have much value if he doesn't raise the money. Wasn't that the major reason why most investors gave him the money at the first place (or any other company in that matter)? To IPO and XX-fold their investments.
Okay, so he didn't. What are they going to do? Complain about it?
Anyway, ethics is about what people should do. If you switch to discussing what people can get away with because of power, you're no longer discussing ethics. If you switch back and forth, using "what X can get away with" standard for people with power and "what they should do" for everyone else, then there is something wrong with your argument.
If you "come for money", you're doing it wrong. You should come for a mutually beneficial business transaction, and that seems to be exactly what Zuckerberg is doing.