Yes, they can ask you if you've deleted things, or if you have things elsewhere, but that's not generally what they ask or look for, or the issue at hand.
Look, you can twist the words however you want. At the end of the day, if a CBP agent or Federal prosecutor clues to the fact that you're using this functionality, their interpretation is almost certainly going to be "'late2part is hiding something!", and they will bring their (considerable) powers to bear in response to that, in order to figure out what that is.
Your indignation about or lack of understanding of that reality aren't going to change it.
Remember: if you're this far down the rabbit hole at immigration, the machine is out of your bag, open, and unlocked. They can take it, while in this state, and image it. If there is evidence that you've been even unintentionally untruthful with the CBP folks, you're screwed. Not only have you lied, but you may have handed over evidence of obstruction of justice/tampering with evidence.
Federal charges like that stack up quickly. If they want to fuck with you, they will.
Now "travel mode" simply removes the local git repository. The data still exists in the cloud, but you have to actively go out and log in to their service to retrieve it. Are you "hiding something" because you deleted a local copy of something from your device? There isn't something on your device that is somehow hidden. It's not there.