That makes absolutely no sense. I'd like to see that nursery worker back that claim up with some valid research article. More often than not, there will be a flush of male blossoms before the first female blossoms. However, I sometimes see onset of female blossoms without any male blossoms to fertilize, so the fruiting fails. (How very sad!
) IMO, it's entirely related to the weather patterns. That squash w/o a growing tip is strange. Keep us posted on how that one performs over time, and if it ever does develop a tip.