I'm unfamiliar with the US legal system but do they really need a jury and a trial to determine whether the claims are barred by the statute of limitations? Couldn't this be decided by a judge before trial?

Part of the Statute of Limitations isn't just on when he filed the claim, but when he found out or should have found out, by reasonable diligence that he had a claim at all.

So the question before the jury has a significant component of "Should he have found out by this time?" Which is a question of fact, and facts are typically decided by juries, in the US at least.

The two parties can agree together to let a judge decide facts like this, but generally, if one or the other party wants it to go to a jury, it does.

I'm guessing part of Musk's strategy was to have it go to the jury, which are often seen as easier to manipulate than judges, especially when a case is weak. Or perhaps his team already knew this particular judge would be inclined to rule against him, so did the next best thing.

Elon argued that even though the events in question took place sometime between 2017 and 2020 OpenAI intentionally hid the information from him until 2022-2023 which is why he wasn't able to file the lawsuit until 2024.

That's what the jury found against - they said he was reasonably informed enough to have brought the suit earlier and thus the 3 year clock should start ticking in 2020 not 2023.

In the US, judges make determinations of law, but juries (in a jury trial at least) must evaluate the evidence to make findings of fact. So the jury would need to make a finding as to when the statute of limitations started ticking based on the evidence, and the judge then makes the legal determination that the statutory period has lapsed.

In the American system juries figure out questions of fact and judges figure out questions of law.

In this case I guess the question was 'when did the incident actually happen' with Elon arguing it was later then Altman.

That's like saying can't the Judge decide who the killer was when he literally saw the video of shooting.

In this case the judge determined that it did require a trial and refused to dismiss based on statute of limitations.