This is just kind of an artifact of how our legal system works. Judges don't generally answer hypotheticals, you have to do it and then see how it pans out.
All that being said, I would be pretty surprised if this outcome wasn't mentioned as a risk to the board or Musk. They're talking about paying him ~10% of the company's _market cap_ as a bonus, and almost double the revenue the company has made in its entire existence. I'm not terribly surprised that a judge looked at that and immediately thought "breach of fiduciary responsibility to the shareholders".
That brings up an awful lot of questions. Does it really take $50B to motivate him, given that his wealth is largely denominated in TSLA stock anyways (meaning he suffers if the stock price drops)? Is there really no one who would do it for cheaper? Firing Elon and hiring a $200M/year CEO would save the company like $50B; why is the board so confident that Elon is going to provide more value to the company than saving $50B on labor costs?
Perhaps paying Elon is the right move to make. I'm dubious, but I'm also not a shareholder, so my opinion does and should mean basically nothing. I do hope that if the shareholders vote to approve the bonus, they're allowed to pay it out. They're adults, they should be allowed to do what they believe is in their best interest.