And that warrants breaking up or nationalizing Twitter how?

Whatsapp's messages are end to end encrypted, so in theory a compromised internal account wouldn't have access to the messages.

Its backups aren't encrypted though.

He specifically mentions world leaders. Also, tons of speculation in the article about things nobody is sure about yet and then extrapolating from there and proposing countermeasures that are off the scale. Security is important. But it wouldn't be the first time a communications service is hacked and assuming a nation state adversary you can consider every tech company in the world compromised to some degree by infiltrating employees into key positions. Those can play the long game and work at it for years to reach their destination.

I would consider anything you entrust to a keyboard or some internet or wireless medium to be in principle compromisable, an in practice most likely compromised in the sense that people that should not have access to that data probably do.

Not good ones.

I dont know many journo's but the ones i do know are Signal users.