That doesn’t make sense, if that were the case it wouldn’t be relevant anymore as humans simply walking on the continent would introduce incredible amounts of bacterias and viruses.
Even with the sterile processing of Moon and Mars rovers have observed this. It’s impossible to prevent, only reduce.
Actually hearing that a country would go to that length makes a lot of this more understandable.
I mean, shit, the Asian Carp in America has destroyed so much natural habitat as a fish, and microbials can cause huge amounts of damage if they are invasive and much more difficult to figure out their source, and harder to stop once it spreads.