My understanding is that is what was happening, bottles removed from checked in luggage, but as you say, it would be nice if someone this happened to could confirm.
True or not, there is just as many stories out there of passengers who have ignored the instructions and got away with it.
The fact that a lot of people who would have taken their own now dont, means it is a success for P&O already, unless we all 'jump ship'...
Andy