There are values associated with pieces. Without considering the position, a pawn would = 1, Knight = 3, Bishop = 3.5, Rook = 5, and Queen = 9. I've not seen the game yet, but if he traded a Queen for 2 rooks that isn't such a bad deal.
Neat, but what stops someone from publishing your PWA under their own dev account? Sure you still control the site and data, but they could publish with inappropriate icons, wording, etc. It seems like maybe there is some potential for abuse.