I think the people who are truly offended by “paddy wagon” comprise a small group. Don’t worry about it.
But they are a wee small group and they always be looking for the end of the rainbow.
Not only don’t worry about Paddy Wagon but also don’t worry about the Navy Shore Patrol “Black Mariahs”——and a whole lot more references to jails-on-wheels. Nicknames go on forever and most are just plain funny. And LL remember when you went out to root for the truckers wearing your stompy foot lights? See what I mean? Don’t worry about it.