Do you mean like if a mate in 2 was passed over? Seems strange to dismiss that since even great players will miss a winning position sometimes.
I think the goal is estimating all legal moves, not all you'd find in a typical game.
It would be interesting to define parameters for a "good move" and see how many there are, though!
Can you define "win situation" ?
I assume he means a forced win. Meaning if the winning side makes the correct moves, the losing side cannot win.
We don't know whether the game is already a forced win for white before a single move is made. It could be. So this system is not workable because we don't know what positions are not forced wins.
AFAIK it's also unproven that it's not a forced win for black. (Not trying to correct you, I just think it's an interesting addition.)