Good tenants are hard to come by. If covering a couple of holes makes them think that they have made a good choice in a place to live, then cover the holes. It'll cost a couple of bucks and take a few minutes.
Again, I'd drop some Combat Gel into the holes and place some behind the range, behind the fridge, and, if they don't have kids or pets, under the kitchen sink.
Then I'd tell them that the house doesn't have roaches, but I'd done a fresh roach treatment just in case one wandered in from the street.
My rental agreement says that the house has been treated for pests before the tenant moved in and that the tenant is responsible for bugs and vermin after they move in. I don't want to be called every time the tenant sees a spider. However, I expect to provide some extra service while the new tenants get settled in.