So, in the context of the OP, Duboin didn't want to insult the opponents, so conceded two tricks in the end position with the opponent on lead. Now we have (IMO) a ridiculous debate about whether declarer should go off for his courtesy. Personally (not being Duboin) and with a nod to Bill, I wouldn't have claimed against most of my oppos at that point in time. Too bad Frances, I 'know' I have sure tricks, but I'm not risking them for the opponents' sake when I can't envisage every pointless defence the opponents might try.