Locked items within layer - able to delete

I believe the ability to only select the entire layer along with the locked object works as intended, for example, for purposes of making a copy. However, I agree that this new behavior of manipulating a locked object is a new problem, though likely related to a similar issue of selecting and/or manipulating anchors within locked or hidden objects (see https://illustrator.uservoice.com/forums/601447-illustrator-desktop-bugs/suggestions/41865163-locked-background-objects-unlocking-moving-when-us). The only way users should be able to manipulate locked objects would be copying, reordering, or deleting the objects directly in the Layers panel (AKA palette). The similar issue was supposedly fixed in version 26.1. But, obviously it touches on deeper issues that need a much larger overhaul.

For now, I recommend moving the objects you wish to lock within a sublayer. When I tested this technique, it appeared to prevent the locked objects from being included when selecting the containing layer. This technique, of course, won't apply if you are trying to lock part of a group, which cannot span layers. And, it's a shame, since that is exactly what I need to do - lock a clipping path, which my colleague keeps accidently nudging.

There was a discussion about this just yesterday. 

With the result that this is by design.