While Frontier may have indicated that the majority play in Open they were silent on how many players play in Open exclusively - mode selection has always been up to the user.
Frontier remain silent on how many players actually engage in Powerplay (other than indications that it's not many) and haven't said much, if anything regarding the mode distribution of those players.
But what then triggered Sandro to pull the open / weighted merits trigger, and (retrospectively or not) say they think Powerplay is consensual PvP?