I've had a kid perform in a cheer uniform once then hand off their Flute and run off with Mom to a contest. No judges said anything on the sheet but one came up to me when I was waiting for the sheets to check out and told me he loved to see that.

I've judged a few times now and it wouldn't bother me one bit. I would probably be more excited to see that kids are able to do multiple activities in your program!