Mettaton function "NEO" was made to eradicate humans, as is stated by he.
Unable to detect signs of humanity in us, "NEO" may have let its guard down.
This is probably also why it never attacks.

Gonna be frank, this is 100% theorization

I'm with the first two comments here
I've no-hit Undyne and no-healed Sans on switch
(Still working on no-hitting that bonehead)

God I'm not active enough uhhh
Burgerpants

Nooo I wanted to taste them :<<

I thought about the time we had over quite a bit of time actually
But I am not exactly a serious boyo anyway :P