A more effective disruptive variation that I missed:
21 ... fxg4, 22 hxg4 Nef6, 23 exf6 Nxf6, 24 Bxc5 Rxc5 (see diagram right) when even Nc3 does not save white's d-pawn - black has Qc7+ to escape any pin subsequent to Nxd5. Thus black emerges with two pawns for the knight and some chances of play against the relatively exposed white king.

The green light shows that the move made is (close to) the best possible in terms of the program's assessment of the resulting position. However if the assessment is that you are the equivalent of two pawns down, playing moves that hold this deficit (if the assessment is accurate) is still leaving you in a lost position. This gives rise to two schools of thought:

School I says that you should always look to play the best objective move. When behind sit tight and wait for your opponent to go wrong.

School II looks to play the best practical move. When behind this may be an objectively inferior move that gives the opponent a greater chance of going wrong. It need not be an outright trap, but by giving the opponent something to worry about can encourage him to make unnecessary moves. These may give you time to coordinate your pieces or achieve some objective. Remember it can be very tempting when ahead to try to stop any play by your opponent, even though by so doing you can end up losing the initiative. When behind, play on this.

In effect School I says that opponents are more likely to make small mistakes than big ones, so your best chance of getting back into the game is to keep the deficit small. School II says that opponents are more likely to make mistakes of any size if you give them options. So give them options even if this increases your deficit.

Naturally RR tries to belong to both schools at once. Ideally he would wish to put up the barricades in positions in which an attacker can easily lose his way, but look for any move with a threat in those positions in which sitting tight is an open invitation for his opponent to take as long as he likes to beat him. Can RR accurately identify which positions are which? No prizes for guessing the short answer to that one!

And when ahead? Clearly missing forced mates is always bad, as it means there are still moves in the game for your opponent to pull a rabbit from the hat. However I'm not convinced that all yellow or red moves need to be expunged from one's play. Making an inferior move that simplifies a position whilst leaving you with an healthy edge can reduce the chance of further error in the game and so may still be a sensible practical choice.

This I think is entirely a matter for the individual. Materially level, yes, and depending on the exact locations of the pieces it is probably close to positionally level too. Sam should not be criticised by either himself or teammates for taking the draw as he clearly believed that was the right result for the game.

Equally when playing in our league players undertake to complete their game in 85 minutes each. If they want a win they have to prove it - secure a mate - in the time available unless their opponent elects to concede the win by resigning. Similarly to get a draw you have to prove it - reach a dead position or demonstrate by the moves you make that you know how to draw the position - unless your opponent agrees the draw.

With an open position and the material available Sam's game was clearly still live, and so he is entitled to play on looking for a win even though he knows his search will be interrupted by his opponent's flag fall. He does not need to be able to demonstrate a complete winning plan. What he is not entitled to do is make random moves waiting for the flag fall - in this case his opponent would be entitled to claim a draw on the basis that Sam was not trying to win by normal means. This claim would need to be made before the flag fell.

There is no moral high ground with this situation. Whether his opponent fell behind on the clock due to an unsuccessful search for a superior line or through the necessity of taking care to live with Sam's quality of play, the clock is part of the game. Mistakes/blunders made under time pressure can and do arise. You are entitled to benefit from these if your opponent falls into time trouble, or to win on time even though you are not ahead at that point.