Iirc, there is feature for auto-use shears, if you have it in your inventory, while treecapitating.

So, can you add same mechanic for Ex Nihilo's crooks?

You have the ability to add them to the config file if you so desire.

Won't work. The crook uses onBlockStartBreak instead of onBlockDestroyed.

Edit: wrapping onBlockDestroyed(...) into if (!onBlockStartBreak(...)) should work. May try to test later.