From rulebook 2nd edition:
A. TRANSPORT CAPACITY
When a unit becomes a casualty it loses its ability to carry any
assets or loads and drops any it currently has on its card.
When a unit that is transporting casualties or assets becomes
Pinned or Paralyzed (neither can perform a Transport Action), it
does not drop what it is carrying, but it will not be able to Transport the casualties or assets any farther until rallied to a status that will allow it to do so.
So, you are right Marc