You posted what I already know. The other link does by no means indicate that there is no gold membership.
There is no gold member or silver member. They are
custom titles which some users are capable of setting.
Read about the 50BTC donation:
https://bitcointalk.org/donate.htmlThere may be some members who got a custom title without donating 50BTC. Regardless, there is certainly not a gold or silver membership you can buy... at the moment.