400,

Take a real good look at the lugs on your SLR bayonet lens mounts and then come back and let me know what you find.

Perhaps a little help is needed so you know what to look for.
To convince me that the bayonet lens system is actually an interrupted thread you'll need to find an inclined plane on the engaging surfaces of the lugs.
Nikon and Pentax SLR bayonet mounts I own/have owned, have the engaging surfaces square to the lens axis, meaning that there is NO inclined plane and therefore no thread system used.