The guy's are just playing with you and welcome to the forum.
Yes a balsa plane can be made into a swappable. You are just building with a different medium but the idea is still the same and pod could be balsa or foam that could be swapped with either type of build.
Swappable is not a new "invention".
In "the old days", when RC and engines were a lot more expensive, there was several kits equipped with "power pods".
Air Combat (1:12 WW2 fighters) are sometimes swappable as you need some planes to enter a game and you might not have so many motors and receivers as needed without a swappable fix.