I guess you didn't read the part that said "Negative Interest Rates", charged directly to your bank account
Lately, the Austrian central bank was rumoured to play with the idea of negative interest rates so the Austrian pension funds quickly brought up the idea of just storing their paper in secure vaults. As long as the costs of storage / protection are lower can the losses due to the negative interest rates, it's a net gain for the funds.
The central bank isn't directly allowed to prevent anyone from just getting their money in cash and while they could delay it by "process", only the government itself could issue a blockage on cash deposition.
If it were me I'd start hoarding euros.