The 4NT is weird, but regardless, N should pass 7♠. In practice, on the run of the spades, east will pitch a club. Since he also has to pitch a heart, this will expose west to a ♥-♣ squeeze. I would say that the vast majority of East defenders would pitch that club. East can kill the squeeze by saving his club, pitching hearts instead. As for the manners, most random players on BBO are awful, both in terms of etiquette and skill. I wouldn't worry too much about the exchange.