Of course, you can assert that the meaning of "steal" only applies to physical items. You are well within your right to do so. You'd be wrong, but you can do it.
To be fair when someone tries to shift the meaning of words everyone doesn't just have to go with it to appease the large corporations trying to do that. I of course don't mean intellectual property rights or copyright infringement, you can perhaps apply the word "steal" there, not when talking about LLM traces which are currently legally uncopyrightable, though. Unless we're actually talking about someone breaking into Anthropic's servers and stealing their files, then again... if you do that you can always just blame the LLM you used.
This is the same use as "the baseball player stole third base". Nobody is depriving anyone of anything, nobody is committing a crime. It is simply: someone has obtained something in a way someone else did not intend.
There's no legal claim being made here, you have made it up.
It's more than that. By claiming that copyright infringement isn't stealing, they're usually doing so to justify such behavior: if the original thing remains with the owner, it couldn't have harmed him, could it?
(And yes, "legally" matters, because we're talking about laws in this thread, not colloquial "their life was stolen" type expressions.)
This question is obviously (hopefully) rhetorical, no need to answer. My point is that different crimes are different. Otherwise literally every crime is stealing, and no other words for different crimes matter. Obviously different crimes are different.
In most U.S. states, the actual crime will be a specific reference to a section in a Penal Code (or, for Federal crimes, the U.S. Code). For civil actions, it's likely to be a reference to a common-law tort, or some Federal statute providing a private right of civil action.
In the case of taking a physical object from someone else, most states call it "theft" in the penal code, or "conversion" for the common-law tort.
But all of this is academic anyway. I'm not entirely sure what your point is.
I edit my reply as you were responding to make my point explicit.