I personally know so many hung Asian men that I can't keep count of them anymore.
However, there are many reasons why it is unlikely to encounter them on LPSG or any similar forum:
(1) They are not native speakers of English, and many of them are either self-conscious about their English ability or find it tedious to try to read and/or write in English.
(2) They are racists.
(3) The ones with small dicks tend to be most vocal and eager to show their penises to anyone and everyone without regard to whether they have the other party's consent. (On the other hand, particularly with Japanese men, many of the hung ones have been peculiarly scrupulous about hiding their penises as well as they can.) I frankly cannot understand why they should be this way, but it has been an obvious tendency in my experience with East Asian males.