Explaining the jokecomic:
The puzzle, as it is typically worded, goes something like this: "Angry and hungry are two words that end in -gry. There are three words in the English language. What is the third?" and the answer is meant to be "language", the third word in the phrase "the English language". In the comic, the person posing the puzzle messes up the wording so that the trick answer isn't even valid. The guy wearing the black hat (frequently referred to on the xkcd forums as "Black Hat Guy"), who is known for his somewhat sociopathic tendencies in other xkcd comics, is upset at either the trick of the question or the fact that the other person didn't even ask it properly (or possibly both), and in response cuts off that person's arm.
As an aside, there are several words in English that end in -gry, including "gry". However, other than "angry" and "hungry", none of them are used particularly often.
In the context of the thread:
The puzzle, as posed, requires a strict interpretation of the rules that does not have much utility since, as others have pointed out, the most meaningful way to count score mid-game would be to consider the score one would have if the game were to end immediately, at which point all of the cards on the player's Island mats would be returned to their respective decks, and hence the Silk Roads would be worth non-zero points.
In a sense, the puzzle posted in the thread is analogous to that asked in the comic. By using a wording that goes counter to most people's understanding of the rules, the solution to the puzzle seems unsatisfying and, perhaps most importantly, out of place in a thread entitled "Easy Puzzles". Hence, when asking Donald for a ruling on whether the puzzle's interpretation is valid, he chose to reply with a link to the xkcd comic, suggesting that the puzzle was based on poor communication and possibly acting smug about it. He may or may not also be advocating for the amputation of the asker's arm.
