The truth of the fact is that this story is no different from the famous story of Laszlo Hanyecz who paid 10,000 Bitcoin to buy just 2 ordinary Pizza, of which we are pretty sure the total value of the 2 pizza back then was less than $50, but yet Laszlo Hanyecz went ahead paying a whooping 10,000 Bitcoins, simply because he never thought Bitcoin will be this valuable today, and that's the exact scenario the German government could have thought when they sold their Bitcoin July last year (i.e Judging from the arrow in the chart above). And as such, inasmuch as you sell and later buy back Bitcoin, it's not a bad idea, unlike when you sell and never buys Bitcoin to invest again, because Bitcoin still has great potential to skyrocket with time.
Maybe Laszlo didn't think bitcoin could reach $1k or $100k at that time but he used 10k BTC to make a transaction just to buy 2 pizzas not because he didn't believe in bitcoin. He did so because he wanted to prove to the world that bitcoin is real and can be used as a currency. Meanwhile, the German government sells bitcoin because of its laws and they need to comply.
So it would be pointless to compare what Laszlo did with what the German government did. These two stories are completely different, one is the sacrifice to create the bitcoin revolution, the other is forced to sell bitcoin because there is no other way.
They don't use bitcoin as an investment like we do, Laszlo uses bitcoin as a currency, the German government considers it a confiscated asset...so in my opinion, this is not a suitable example to talk about holding.