Sounds more like he was stuck in gear, rather than dropping a chain. Personally think this "etiquette" is somewhat BS, unless the mechanical is caused by outside influences (Tacks, crowd etc) then to an extent it is yours/ the teams fault so attacking is fair game.
It's like the card game 'Asshole'. Every round the asshole has to give the president their best card. It makes it really hard to move up from asshole and really easy to stay as president.
I don't know the game and it doesn't sound like much fun, but it does seem like a fitting metaphor for the GC race: the person in yellow gets special favours because jersey even though they're the one in the most secure position.
Sounds more like he was stuck in gear, rather than dropping a chain. Personally think this "etiquette" is somewhat BS, unless the mechanical is caused by outside influences (Tacks, crowd etc) then to an extent it is yours/ the teams fault so attacking is fair game.