Curl,
Yes, that was my point exactly.
At first glance the bayonet mount looks similar to an iterrupted thread but close examination will indeed show otherwise.
The interrupted thread system is well suited to joining two surfaces which will be required to endure high loading forces.
Some take down bolt action rifles use the interrupted thread system to secure the barrel to the receiver and yes indeed, the A&WC Webley double rifle action uses an interrupted thread as part of its its third bite system.
A bayonet mount system would not be suitable for either of those tasks.

Both the interrupted thread system and the bayonet lens mount system draw two surfaces or flanges together as the lugs are fitted and rotated.
They both start off with a clearance (existing between the faces) which is taken up as the rotation is completed.
The BIG difference is that the interrupted thread system draws the two surfaces together by using the helix on the flank of the thread and achieves a solid lock up which has taken up all the clearance.

On the other hand the bayonet mount has no helix and relies on spring pressure to hold the two surfaces/flanges together.
The clearance has been taken up by spring pressure alone and any force applied to the parts involved which exceed this mild spring pressure will easily create movement at the clearance in the joint.

The bayonet lens mount on SLR cameras is not required to endure high loadings.
It is meant to provide fast changing of lens types with precision and ease.
This it does extremely well.