I think I can speak for @tylrwnzl here, but he'll correct me if I'm wrong.
"Composite" is not meant to exclude panorama stitching, which is still a "straight" photo that simply overcomes the lens/camera limitations in field of view.
Instead, it's meant to exclude photos created from two or more unrelated images, creating a view that couldn't actually be seen by you or the camera. For instance, taking a field from one location, and a mountain from another, and combining them. Or taking clouds/sky/moon from a photo you took in Colorado, and merging it with a river from Utah. Things like that.
This exactly. I will include this as a description for the August contest.