Heathrow security defuses deadly rice-milk threat by insisting that it be decanted into baby-bottles

My parents flew home to Toronto from London yesterday, along with my brother and sister in law and my two-year-old nephew, Jaxon. At Heathrow 3, they encountered this bit of security theatre, as recounted by my mother:

Customs set aside Jaxon's diaper and food bags. Neil tasted the liquid that
had been poured into Jaxon's sippy cups – no problem. Then the guy said that
the 1 litre Rice Milk boxes couldn't be brought aboard the plane since they
exceeded the amount of liquid allowed (there was one full 1 litre box and an
opened box). Tara explained that Jax couldn't drink milk and they needed
this for the flight. She indicated that they'd be willing to taste the milk
but he would have none of it. Then a supervisor came over and said that if
the milk in the boxes was poured into baby bottles they could bring it on
board. So I was allowed to go to Boots (after going through passport control
and shoe control) to buy baby bottles for the Rice Milk to be poured into.
This I did and the milk got poured into the bottles and we were all allowed
to go (after Neil was asked to taste the milk and taste Jaxon's liquid