Yes! Well let me be a bit more clear. The FCC has a process for, and indicated they would likely approve, a special temporary operating license for such a device given that it would only operate for a short time (during the break-in) and not interfere with the thieve's or neighbor's cell phones as it would respond with no compatible roaming network. Also it wouldn't do any sort of interception or monitoring other than the tower ping.

It would also need permission from the licensed spectrum holder, that could be harder to get.

But yes, completely legit with the right paperwork.