I didn't think the cargo containers were even the slightest bit sealed, so they would likely decompress about as fast as the external environment (i.e.the hold).
We're talking about one of these, right?
Dimerco - your china logistics specialist
Has sides on it.
Capacity is 14,300 litres. With the hold going from something like 10.9 psi to 4.3 psi that container suddenly contains something like 36245 litres extra of air.
ie. Is under 6.6 psi o pressure.
This air has to escape through the small gaps around the doors of the container almost instantly, i it can't then it will blow th container out somewhere.
NB. Sums done in a rush, may be off a bit.
This is my understanding, have been wrong once or twice tho'. Just the once or twice mind!