Hmm going to wait and see how this plays out, maybe it's time to look at alternatives, assuming that my custom domain email isn't somehow locked to them.

Last time I checked, hacking was still a crime in most jurisdictions - even if the target is considered a geopolitical adversary. This sort of activity is also against the Proton ToS. Once KrCERT and Proton were alerted to this activity, they would have been legally obligated to act.

That's not to say I feel any sympathy to the target - who by all counts has done a fair bit of damage. But this sort of hacktivism / vigilantism simply isn't helpful. There's a high likelihood that one or more nation states / law enforcement agencies may have had active operations directed against this threat actor derailed by such activity.

tl;dr - If you're going to conduct such activities, practice proper OPSEC. And don't let your desire for attention / recognition take priority over staying on the right side of the law.

From the Proton/X discussion in the Intercept article

"Big Tech CEOs are tripping over themselves to kiss the ring precisely because Trump represents an unprecedented challenge to their monopolistic dominance.”

They don't know how this is going, from what I see Trump threatens something not to change something, but to get something. If there is any anti-trust drive it's there to shake the tree, not to break up big tech. Trump loves big US corporations, like those in the 50s and 60s, those pre-Bell-breakup.

So, is this a case where Random Cybersecurity/Tech Group mistakes responsible disclosure for hacking, and then reported it to Proton, which took their word for it and disabled the account?

A related submission a few days ago with similar Proton response on twitter: https://news.ycombinator.com/item?id=45201153