90% of the people here don't know Peter Chao. So yeah they'll think he's retarded.
I really don't watch Peter Chao and I think he's stupid half the time, but given he's a well known vlogger in the Asian American community, the importance of the video is increased. As for the 10x other random responses that people keep posting on Youtube... so what? Who cares? They're just random people. Maybe they're funny today, but so what? Peter Chao is a Youtube celebrity. This is like if KevJumba or WongFu decides to reply.
It's like making a racist black joke and having Dave Chappelle respond. If you don't know him, then obviously you won't get why his response even matters