Ah, I misread or misunderstood what you wrote. The more I think about it, the more I'm inclined to agree with you guys a little more. Mindless means not having to think or take anything into consideration. You just spam click. So your mono-Fire AI3 grinder is definitely mindless. A Lava Destroyer deck (without Cremations) would be mindless too since you just click anything that is clickable. But I wouldn't say that a Graboid deck is mindless. You can't just click anything this is blinking. You have to make sure you only click to evolve Graboids and not burrow Shriekers. That little iota of thinking takes away the complete zombie mindlessness. But still, both those decks would be more mindless than this poison deck is.
I had another almost mindless deck idea. What if you had just SoGs, Towers/Pendulums, Fire Shields and Fahrenheits? Of course Wings and Phase Shields can screw you. But maybe . . . I'll have to go test it now.