As long as they make smart investments, selling is not a bad idea. But just because they had some gap and wanted to sell and cover for it to pay for the difference is not a smart move.
Germany did that, UK did that too, they sold and used it to pay for the difference in the spending the government has and the income it has, so that was a wrong move. Sure if you want to sell, so that you can buy cheaper and do better then that is a good move because they can buy cheaper later on.
Don't know about the UK but I am not going to forget about Germany, they sold at an average of $53k. Do you think Bitcoin will dump lower than $53k? I don't think so, even if price dumps lower than $53k, they made a bad deal. First, they sold too early, which causes panic in the market and starts a chain of selling too but that was good for the long-term move.
Anyway, later they showed interest in having a strategic reserve and buying bitcoin. At least they are not feeling anything they should be feeling and made a statement about the strategic reserve. A lot of countries when sold they did not knew what is the future of bitcoin is! That's my theory, but now they do.