Guy

I think he was improvising.

He wanted to hit on a hot chick who were before him in the check-in line up.
But she was taller than him. So he managed to raise his height with whatever he can find in the airport.

Don't you see? you can't find a new pair of "thick" shoes and insole or lego blocks;
but there is plenty of batteries and metal plates you can find in the airport.
(Look around in the airport, there are lots of metal plate with no sharp edges in the area)

I suggest him to use my method. (which properly will cost more)
Playing cards layered them crewed bubble gum (suggest non-mint non-sweet flavor) .
Put it in the shoe and wear it and step on it to make the heel impression.
Take it out, clean and take off the excess gum and add more layers  if needed.
At last, use the blow dryer in the bathroom to dry the gum off and harden it.
Instant insole DONE~!