Nope. It's not an error because the Olympics are not about his personal glory. It is about national pride and federer wants to make sure he can give as many medals as possible.
This way, he has a chance to have two gold medals. It doesn't matter if he wins the medal in singles or doubles ( contrary to what nadtards might say, Olympic medal isn't important in ATP).
Also, it's a short tournament and fatigue won't play much of a role. Serena won both singles and doubles in Wimbledon, which is a long tournament.
Excellent 1st thread btw, and welcome to the board.
I am sure he wants to win singles medal much more than doubles medal
You can not be clear in mind if you doubt that.