My interpretation of the challenge after the review (I could be wrong...)
The refs originally called no goal due to goalie interference. Then they were reviewing to see if the puck went in the net before the whistle (or how exactly it went in). They came to the conclusion the puck went into the net legally, and before the whistle, so the call on the ice was no goal due to goalie interference (because can they review goalie interference without a challenge? I imagine not?).
So Green challenges goalie interference, which they uphold, and it's no goal. Worthwhile challenge, IMO, because that was probably not goaltender interference.