MP, best hand South
Choice of passing the 1H response turned out to be a successfull bit of operating that I would not do at a face to face table, but that is not the point of interest.
This was at a 55% rebate game with only two other contestants, neither of whom could avoid getting to 5H after the following almost-but-not-quite identical auctions:
I have a modicum of sympathy. In a face to face game I can well imagine my replicating the auction up to and including South's 3H, after which there is no escape.
I suppose that it is possible that if South has at least 5-5 in Hearts and Clubs, then North might never want to defend 4S, even if South offers a double of 4S. Personally I would stand the double. But should South's 3H show 5-5? Is there no hand with lesser shape in which he is sure that he does not want to defend 2S undoubled? Presumably pass would have been non-forcing.
Minor point - East's final pass of 2H at my table seems a bit wimpy. Maybe he fears pushing us into 4H. GIBberish does after all require opposition bidding to bid games.