I'm sure that if you glue the spoiler to the trunk it will stay on, but I don't think it will be enough to make the fit look symmetrical. The bolts actually "pull down" on the spoiler so that you can match the height with the rubber pieces on either end of the rear fenders. Also, the bolts assure that the fit is perfectly aligned with the back of the trunk lid. I guess you could align it manually, but I can see this being difficult, as one small movement could cause a poor fit. If it were me, I would try to refurbish the spoiler and use new bolts.
Best regards,