This is correct. But IIRC (it's been awhile), the device also sends it's programmed hardware id to the network, which in theory would allow the device to be tracked to some extent after flooding the network. The emergency call itself doesn't require a sim or active account (atleast in Canada).

I do have a recollection of watching a network outage ticket once years ago, where someone dropped their phone in a puddle which apparently caused the device to put out interference which some techs managed to track down.

There is also this case from Florida: https://www.techtimes.com/articles/161146/20160526/florida-m...