NewTek can't host it.
Even though someone took copyrighted material, reproduced it and distributed it, there could be some legal gotcha in some country that causes the pdf itself to be copyrighted by the person who created it. (maybe they added or changed something, who knows)
NewTek can't take that risk for no benefit, it's not worth it.
My personal (not NewTek's) opinion is to mirror the heck out of it and they aren't going to waste their time and money to go after someone for an ancient users manual.