Your argument is that because one thing which some people considered a conspiracy theory, but most experts did not, was true we should believe all of them?

Yes, there’s a hardcoded password. The field has a long history of people adding those to make support easier, and I’d bet a lot more that that password means someone with that name worked on the mydlink project than that the NSA put it there, just as most burglaries are routine crime even if the CIA or FBI has been known to quietly bug houses.