I'm thinking you're right. As much as I love the '87 show, the guard was the weak link. (I've always wondered if that was a direct consequence of having marched practically no guard the year before.) That entire rifle sequence was mostly strap work. Inventive, but it also revealed an inherent weakness in the rifle line; it was obvious they couldn't let go of their equipment. Which made me wonder about the wisdom of having a rifle line. I mean, if they can't toss, then why have them in there at all? If you have to have a separate section, then why not go the route Santa Clara had already gone and put them on some other prop? Another thing that happened the way it happened, so what's the point of questioning it now? Just how my brain works, I guess.
I WILL ADD: not a strong guard and in todays world the guard would have kept them from winning......
That said, 87 is still one of my all time favorite Cadets show, the guard did help sell the show, and one of the best COSTUMES ever put on the field. (lucky they did't give the guard a score back then).