No he did not. Unless you are 5 years old "Duh, I knew that" is not the same thing as admitting fault:

"Duh, it's fake. Obviously, it's possible to set your system clock back. I was so intrigued I wasn't thinking clearly, even after I pointed this very "attack" out during the Ed Snowden GPG affair. Sorry folks, maybe if it were timestamped in the blockchain."

He played it off and says the real answer is obvious. Then he provides an excuse for not recognizing this obvious truth. Finally to make matters super strange he informs us (w/o evidence) that he was the one that pointed this "attack" out to us during the Snowden affair.