I don't recall anyone ever advertising Bitcoin as a stable currency, and institutions/companies would've absolutely known this. In fact, I actually suspect this is why some of them got involved in the first place. El Salvador for example, likely got involved anticipating a upward trend, so they can better their country very quickly. Obviously, at the moment the opposite has happened, but if they were to hold on long enough to see x2/x3 their money, they could really launch their country, quicker than they would be able to elsewhere.
Perhaps I'm not up to the news but I did a quick search on Google (a shallow one though) and it looks like El Salvador hasn't issued their Bitcoin bonds yet. They are still blocked by bureaucracy and politics as far I see. If they can manage to successfully market the bonds at these prices they would be well positioned for the next bull market. Well, that's not a sure thing of course, but yet 5x'ing their money when BTC gets to $100k would be quite a treat

They'll be back, but the volatility has always been a issue for companies to start accepting Bitcoin. It's why the likes of Steam, Wikipedia and various other companies pulled out after a certain period. This isn't anything new at all.
Aren't there payment processors out there who instantly change Bitcoin to fiat in the backend for a fee? I know at least one that offers a solution like this for ecommerce websites. This way businesses who do not want to stack up on Bitcoin can enable users pay using crypto and offset the volatility risk.