This lesson teaches how to sacrifce material to expose the king to go for an attack. In the example studied, the knight can be taken for free with the rook because if it is taken back a quick mate follows. Capturing with the queen is considered incorrect because "this sacrifice is too much! [White] will need the queen for the attack".
While this is the more conservative way to play, and the way to teach advanced player that play mostly rapid and shorter, this is technically false, as pawn takes queen also leads to a longer mate in 12, after 2.Rhg1+ Kh8 3.Bc3
So black can't take back the queen either, ad taking might be the best move if black plays perfectly and avoids the mate. Among other things, it allows Bc3, bringing one more piece to attack the ennemy king.
Stockfish depth21 evalutate the position to be at +5.08 after queen takes, only at +4.28 after rook takes.
