The knight alone cannot hold the corner. If the defending king is far away, the rook pawn promotes even though the bishop is the wrong colour, because the knight cannot both block and avoid capture.
The wrong-coloured bishop draws only in combination with a king in the corner. Here the black king is on g1, seven ranks away, and the knight on a1 is in the opposite corner. The knight must try to stop the h-pawn alone, and a knight is a poor blocker of a rook pawn: it needs to reach g8 or f7 (or capture the pawn), and every square it uses can be covered by the white king and bishop.