Are you sure about that? Are you speaking from experience? Lamination is a good way to protect paper from unintentional spills or greasy fingers.
Usually, if the only person claiming something without any actual backup is just a random person on the internet... take it with a grain of salt.
I'm not sure why laminating a paper wallet would be any worse than not laminating it. I can't think of a good reason for that.
Further, he suggests to store the paper inside of a book. That is fine as long as he doesn't rely on it as a security fasctor.
But putting a laminated paper inside of the book wouldn't have any disadvantages.