That sounds like it was absolutely terrifying and I'm glad her son is okay.. but to swear off all bounce houses forever and to warn other parents about letting their children play in bounce houses is a bit dramatic. I don't blame her for being afraid of letting her children play in them in the future, but it was not the bounce house's fault. Yes, the rope should have been secured somewhere, but it sounds like that wouldn't have happened had the other child not wrapped it around his neck. I cannot believe she did not find out what child did that and have a talk with his parents.
We go to bounce house gyms regularly and DD loves it. But I am always right there with her and making sure the kids playing around her are being safe. It drives me crazy when parents just cut their kids loose and don't know where they are or what they are up to. This situation could have been avoided with a little supervision.