Seem like ai_mining only work with mob that have pickaxe. I testing with a bunch of other mod and only pick-wielding mob can break block, barehand or tools like hammer or chainsaw doesn't work.

Pasting my reply from curse here for good measure (I had just made it so you didnt miss it or anything)

"Should probably work without a pickaxe, though AI task injection can be tricky with custom mobs, their AI task ordering and priorities might cause their custom AI to override my digging AI, thats more likely whats happening, I need to expose the priority number to the cmod config json stuff so you can tweak it better, or find some automagic way to make it just work better. Its on the todo."

TODO for future self: add task priority number and/or task replacing feature to all AI adding cmods.