Until we get confirmation, I'm going with Ortega just guessing wrong. It's the simplest solution.
Starfleet cruiser showing up at Pandora was going to be treated as an act of war, wouldn't they have been better off stealing literally any other ship to get there? The trip to Pandora and even the beam-down are skipped in a scene transition. The dialogue told us that it would be really bad if a Starfleet cruiser went there, and then it turned out they could have done the thing they intended to do with any old ship. It's all so contrived.
They were in the Sol system. There would have been an abundance of civilian ships to steal. Hell, we've even just been told this episode that Starfleet shuttlecraft have reasonably fast warp engines. They'd be a lot lower profile than a starship, and the remaining half of the bridge crew who somehow manned the Enterprise this episode would fit just as easily in the Galileo. And they might have got one of those just by asking.There were no non-Starfleet ships available to them in the moment, so that wouldn't have been a solution.
The only reason it worked out the way it did was because they prevented the fake vessel from completing its mission. Just showing up for fun would've been a direct treaty violation.
Possibly. Ultimately, I fault the plot less simply because they had the foresight to have the security officer specifically request the whole starship, despite the salient points made already in this thread whereby a smaller ship would typically make more sense. All I have to do is say "Well, La'an thought it necessary to ask for the Enterprise," and my mind is at ease, almost without regard to whatever her reasoning actually was. It's enough for me to assume she had reasons.I believe her thinking was more “something big is going to happen” and a top line Federation starship gives you more options than a shuttle.