Can we conclude that not all legendaries are knowledgeable in the forum? I myself was scared to answer or quote legendaries when I initially joined the forum.
Not really.
Legendary members can also be spammers, trolls, and even scammers, like any other member ranks.
We all know the fact that bitcointalk forum accounts can be sold and purchased, so you can never be 100% certain if account didn't change hands.
Reaching Legendary rank is not ''the end'', you can still become DT Default Trust member, some people even became moderators, and you can always contribute forum with reporting spam.
There is no rank above Legendary for now, but I know some excellent member that are not highest rank and they still write great posts and make great forum contributiuons.