I agree. When I am quarantining fish or corals using a HOB or canister filter, I use use water change water to rinse the sponge or foam out so it does not kill the beneficial bacteria like fresh water does.
It kind of depends on what the filter is being used for. If it is strictly used a mechanical filter, than tap water would be fine. If it is also used as a biological filter, then no (as the previous posters stated).
I just rinse mine off using the backyard hose. I don't use my filter for biological filtration, if you are just using it to cleaned up the water don't worry about it.