autocross still isn't "racing" so that won't matter, and as long as i am being instructed at an open track event that is a car control course as well, also not "racing" by definition.
i have seen many people break parts at events and get them fixed under warranty. there are legal definitions of what constitutes racing, and none of them prevent a person from doing any aggressive driving on a track if it is under an instructional basis.
if parts broken through aggressive driving alone voided warranties hardly anyone with an f-body woudl ever have any warranty service done to a vehicle.