I have thought of a way to lock the button but it would take finding/manufacturing a clip to fit over the shaft of the button between the button head and the slim itself. I was looking at my nasal spray bottle and it has one but it's just too big. That would make it a little more portable for pocket carry.
Like a cotter pin? I know some of those are tight enough that you dont have to necessarily drill a hole to make them work, they just slip around that shaft/bolt whatever.