For example recently in Greece the exact thing happened that people always worry about: home ownership was suddenly being heavily taxed, because those house owners have little way to hide their assets.
In general governments try to prevent the population from using alternative currencies (usually it is illegal). So if in an economic crisis gold would become too much of a live currency, countermeasures by the government seem very likely.
Anyway. Turning "hoarding" into a dirty word is one of the last signs an economy is about to tear itself to pieces, just before the baseball bats come out and shop windows start getting smashed. Stay classy though!
> That's a) impossible
Well, that's prima facie not true. It can indeed be possible for theft and violation of private property to be a net good for the economy as a whole.
Again, I stress, I have no idea about this case per se. It's an interesting thought experiment though, as to when the government taking something away from private citizens like that can be good on the whole for an economy.