Yeah because Harry had a piddly threshold, had that been the Carpenters, the biggest threat of Toad crossing the threshold would have been slipping on the the ectoplasm before it sublimated. Not all thresholds are equal and Jim has been deliberately vague on the point in book to give himself wiggle room.
Yeah, Jim has always maintained the stronger the family, the stronger the threshold. At that time it was just Harry, Mister, and Bob, I am sure it is much stronger now with the addition of Maggie.
