To be fair, Atticus only knows as much about Giles as he's seen on a television screen as well. Just a different screen.

And a different Giles.

"Rupert Giles? Like...Giles Giles? Like Buffy's Giles?" Atticus asks as he shakes the offered hand. (His own grip is firm and just a little too warm.)

"You must have won before I got here. I don't remember seeing you on the videos." He's only been watching the ones of the new Tributes, not quite curious enough about how things used to be to actually go back through the older records.