The SPS test, while on the ground, is an integrity test of the SPC system. The auto pilot is not engaged whilst doing this test (with most CRJ operators). Pushing the (red) AP Disc button on the yoke, causes the pusher to "push" the stick forward as it is designed to do.
I'd be surprised if holding in the AP Disc button during a pusher event, prevents the pusher from doing it's thing.
But I'll try it and get back to you.
