Change of rules, maybe?
Dunno if the rules have changed since the early 1970's, but worked with the RNZAF loadies in Wellington when they were moving cars & people to/from Blenheim during a Cook Strait ferries strike. We drove the cars on & waved the a/c goodbye, then backed the cars off the Andover or Herc that had just pulled up. Nothing ever mentioned about pre-flight draining of fuel. Would have made the whole operation ponderously slow.
Or are the military rules different from the civvie ones? I seem to remember shoving the occasional vehicle out the blunt end of a Herc in flight and I'm pretty sure "batteries were included" (=gas in fuel tank)