Let us use the original argument:
- Premise 1: If X is good, then the question "Is it true that X is good?" is meaningless.
- Premise 2: The question "Is it true that X is good?" is not meaningless.
- Conclusion: X is not good.
Now we put the oppossite:
- Premise 1: If X is not good, then the question "Is it true that X is not good?" is meaningless.
- Premise 2: The question "Is it true that X is not good?" is not meaningless.
- Conclusion: X is good.
It can't be true that X is good and not good at the same time. This means something is wrong with premises.
Wikipedia states that Moore begs for question in second premise. But I don't see anything wrong with second premise. We can replace goodness of X by any other statement and thus say any question is meaningless. But actually, it's unintuitive to think that no question is meaningful.
Therefore it's in the first statement - "If X is Y, then the question "Is true that X is Y" is meaningless." What exactly is wrong in such a proposition?