Actually, I don't think you were given a line of crap.
From their response, I don't think they were denying that it's threaded but simply explaining the thread pitch is inconsistent, hence, there isn't a one-size-fits-all sunshade for it. And, attempting to do so would mean irate customers venting on the internet, complaining about the quality control. grin



[Linked Image from i.imgur.com]

WWP53D