After reading the entire discussion chain I believe the consensus is this: We don't have enough information to say whether this is reliable or not, but it's leaning towards no.
It seems people undergoing this method get a painful asphyxiating feeling for a few seconds (thread is unclear about whether this occurs at the beginning of the attempt or the end) which universally causes them to back out. It's possible they didn't mix it correctly, or didn't wait long enough for the CO2 to fill the bag, or any number of other points of failure.