You're reading too much "between the lines".

My claim "metaphysical questions are meaningless" was not supposed to taken seriously and I won't try to defend it. A better saying would be "metaphysical questions are meaningless for me". A more correct saying (using the context of my original comments) would be "inside a scientific context, metaphysical questions do not add value".

That's why I added the second question. I know the limitations of science, I don't know the limitation of metaphysics (if there is any).

Given a scientific concept X (circadian rhythm, for example) how much is metaphysics relevant to X? (Note that I'm asking about X itself, not the nature of science).

without trying to twist what people are saying

His words:

Rather than translating the term as "after nature", Christian thinkers translated it as "beyond nature", which is what gave the term metaphysics a second level of connotation about spirituality, God, and whatever is beyond the scope of a natural inquiry.

This was the definition of metaphysics that I used, because I was discussing in a religious context.

and

I personally think metaphysics shouldn't be scientific knowledge