confusion about blitz rule

Yesterday I played a blitz game,

the final situation is shown in picture1. My opponent ran out of time and the system judged "drawn by timeout vs insufficient material". But theoretically, there are legal moves (even though foolish) leading to checkmate.

For example in picture2:

1.Kb3, Kb1
2.Na3+, Ka1
3.N4c2#

My friend told me that unless the black is an idiot, 2 knights cannot mate(I agree), so it's fair(I don't like it). Is that true? Considering the situation in picture3 , it will be a draw if the black had enough time and didn't make blunder. But what if the black used up time? I think he is more likely to get a losing.

Gentlemen, what do you think of my encounter?

Mate with 2 knights is a help mate, so yes its declared a draw.

#3 i a draw.  IF black runs out of time, white has mating material, and gets the win.