Regarding Proton:
Companies know that most threats that customers make, are empty threats. It takes work to migrate an email address, and many people are lazy and—when push comes to shove—not willing to spend that effort. So, in the end, many customers will not act upon their threats and companies will ignore their customers' threats.
As Jaime Lannister said in Game of Thrones, "Only a fool makes threats he’s not prepared to carry out."
Bad demand: "Either the CEO goes or I stop being a paying customer."
Better demand: "I just canceled my subscription. When the CEO is gone, I might consider coming back."
Bad demand: "I will cancel my subscription if there is no apology from the CEO." (The customer didn't even state a deadline.)
Better demand: See above.
Immediately put them in a bad position and make them work to get out of their bad position. Don't just threaten with putting them in a bad position while you let them stay in the good position until you act upon your threat. Which you might never do.
Also, when someone shows you who they are, believe them. Don't demand apologies from a CEO who is a notorious disappointment, demand a different CEO.
Especially if you don't even set a deadline, they will assume you're only bluffing. You're making a fool of yourself with empty threats, and they will accordingly play you for a fool. Make better demands if you don't want the CEO to laugh at you.