So at least for .com and .net there's a responsive third party with procedures to work around failing registrars.
On the one hand, using national TLDs can be a problem if the area you live in is no longer considered part of your country (I imagine .ua owners may have that problem in the future with the way things are going). On the other hand, using TLDs like .com/.net/.ai/.io puts your domain under control of foreign law enforcement (US for .com/.net, UK for .ai/.io).
It looks like .io will change jurisdiction. Another thing to consider with regards to jurisdictions. There is a good argument for you own national TLD.
That said, a lot of ccTLDs are not that restrictive. Anyone can register a .uk for example (so, Scottish nationalists have one less thing to deal with in their plans).
In the case of Ukraine they will probably want to allow people in any territory they lost to retain .ua domains as a way of maintaining a claim (that is assuming their rules are restrictive in the first place).
Not to mention the risk that someone else takes possession of said email accounts and domains, in which case they essentially own every account you have that's bound to that email.
In fact the entire reason I stay on free email from a company I don't like is because I think it minimizes the chance I lose access to my email. My conclusion is essentially the exact opposite of the article.
A registrar banning you doesn’t remove your ownership of the domain. File a complaint with ICANN and you will get it back shortly.
was it a very distant location to head out to?
Mandatory reliance of services on other services (whether it is email, phone, or a more explicit identity provider) is generally unfortunate. I think it is best to not look for a perfectly reliable setup, as it is unachievable, but to keep in mind that they are not reliable, to have recovery plans and fallback options if possible, reduce dependence on online services, especially those depending on others. Though a personal domain name still seems more reliable to me than that of an email provider.