That depends - they probably have to do whatever is in the best interests of the non-profit, so if they explain the motivations behind why they feel they are acting within their responsibility then that could probably help a defence.

IANAL though. I assume you can make a case though that says OpenAI needs to be able to raise sufficient capital to maintain its current market position, and these changes are required for that, and without maintaining market position the non-profit arm will not be able to achieve its aims.

As they have to act in the interests of the non-profit arm, I assume there must be an element of mens rea (state of mind) - the same action could probably be illegal or legal depending on why it was done.