If you happened to be a literate English speaker, you might become confused, and think that this shaped ink somehow meant that box B contained the diamond.
A sign S “means” something T when S is a reliable indicator of T. In this case, the clever arguer has sabotaged that reliability.
ISTM the parable presupposes (and needs to) that what the clever arguer produces is ordinarily a reliable indicator that box B contained the diamond, ie ordinarily means that. It would be pointless otherwise.
Therein lies a question: Is he neccessarily able to sabotage it?
Posed in the contrary way, are there formats which he can’t effectively sabotage but which suffice to express the interesting arguments?
There are formats that he can’t sabotage, such as rigorous machine-verifiable proof, but it is a great deal of work to use them even for their natural subject matter. So yes with difficulty for math-like topics.
For science-like topics in general, I think the answer is probably that it’s theoretically possible. It needs more than verifiable logic, though. Onlookers need to be able to verify experiments, and interpretive frameworks need to be managed, which is very hard.
For squishier topics, I make no answer.