Satoshi Nakamoto remained active in the development of Bitcoin until late 2010,
That's not entirely true. According to the Satoshi-Sirius emails, satoshi was active in Bitcoin development at least until February 2011, although he was no longer active on the forum.
after which he handed over management of the project to Gavin Andresen and disappeared,...
No.
How come the name of Gavin Andersen is not seen anywhere
What do you mean? You can find his user profile here:
Gavin AndersenFrom my research
SIRIUS
joined the forum on
January 16, 2013, 07:30:36 PM
No.
Sirius joined
this version of the forum on November 20, 2009, but he was active even before that on the sourceforge.net forum, as was satoshi.
CYRUS
also joined January 16, 2013, 07:30:36 PM
That's right. I believe Cyrus is the latest addition to the admin staff, probably promoted by theymos.
By this findings it is evident that the administrators and moderators running the forum did not even meet the founder in the group
That's not true.