If player A is offline for 60 seconds, then player B can claim the victory.
But if player A plays a move before the victory is claimed by player B, the possibility for player B to claim the victory disappears.
Why?
Edit: for clarity sake I used the terms player A and player B.
Because they obviously haven’t abandoned the game if they’re still playing moves? 
Isn’t it that the player who could claim victory played the move and now cannot claim victory (after another 60s say) even if the opponent is still offline.
I edited the original post: for clarity sake I used the terms player A and player B.
Well then the answer is as BHydden said. If player A is still playing moves then they are not offline.
