Demanding evidence isn't the logical fallacy you are committing. That assertion is fine.

The logical fallacy you are committing is claiming that lacking current physical evidence of the plates is evidence of a hoax. Which it is not.

For example, I could claim that aliens appeared to me. Should I be believed because I merely made the claim and have no proof? Obviously not.

If I then ask for proof and you're unable to provide me with any, have I proven that aliens did not appear to you? No, I have not.

However, you would still not have proven that it happened, we only have your word, and I'm not obliged to believe it. But, I've certainly not disproven your claim on the basis that you couldn't provide some type of physical evidence.

Tying this back to Joseph Smith and the plates. His claim alone is not proof that the plates existed. You are correct in saying that.

However, others claim to have seen the plates and maintained that testimony on their death beds, as did Joseph himself. One of the three witnesses even aided or attempted to translate a portion of the plates (if memory serves).

Emma Smith claims to have seen the plates on the table covered in cloth and saw an edge of it.

There are also individual descriptions of the appearance of the plates from many of the witnesses (once again, if memory serves).

I'm not citing these as some type of irrefutable proof that the plates were a written record of an ancient people here upon the American continent. But certainly, Joseph Smith was not alone in claiming their existence.

Point is, currently lacking the plates is not evidence of a hoax, therefore, your rebuttal is not strong, instead being a logical fallacy, we are consigned to consider the other points which you refer to as "not strong."