The point is that you don't know, at the moment, and this is where the question arises: you don't know.
You have the ability to get the telephone company to tell you who's been making those calls. You have the ability, even if that person has an unlisted number. Even if they're using a cellphone, you do have that ability currently to do this. You do not have that ability to ensure that ISPs can tell you who is using their service to do this. You don't.
So I think your RCMP officer must have had a nice way of getting around some of these. I have heard from the police themselves that they haven't and that they need this tool.