This is not a safe assumption. You're just one crazy person willing to harass the family of whoever runs the registrar away from being 'too difficult to work with' and getting your account nuked. They don't charge enough to stick their neck out for you.
We're also one button press away from thermonuclear apocalypse.
Knowing what's more likely and what's less likely is still useful information: social media turning bad is a daily occurence, while dns registrars' family members have been safe for a pretty long time now.
The registrar does not own the domain, they just registrar it for you. If push comes to shove they need to let you transfer the domain to another registrar of you choosing after which your users will be able to reach you the same way as always.
Not so much with social media where the respective tyrant has a TOS that makes it clear they can tell you to pound sand whenever they feel like it.
