"Cooper DeJean said he was trying to “keep my balance” with his left arm."
It would be taken care of if you just let the returner get hit if they sent an unclear signal. However, as someone else noted, they error on the side of player safety. If that means a convoluted rule leads to an occasional suboptimal outcome such as the nullification of a great play like the one in question, TPTB are ok with that. I personally disagree with the pussification of the sport, but whatever, I am not going to win that argument these days.
He wasn't trying to keep his balance. If he said that he lied. He was clearly pointing out where the ball was going to land so his teammates didn't run into it, but probably knew saying that wasn't going to help his cause.
Did you actually watch the video replay? Although he was initially pointing to the ball with both arms, he stopped pointing with his left arm and was clearly waiving that arm back and forth, not pointing with it.
