unfortunately, I have no idea why visibility, a generalized on/off property that doesn't depend on the layer content, is connected to the state of the paint within the layer boundaries.
AR tends to handle certain things in its own way, so I guess some logic is there still.
locking all layer properites also prevents flipping canvas command for that layer - I flip back and forth very often during pencil sketching and early color blocking in...
this is where using "lock transparency" option alone is more convenient - having a custom keyboard shortcut eventually makes locking/unlocking sketching layer linework a more convenient and a very fast thing. even if you accidentally dab with some paint over there, a quick cmd+z will take care of that.