Nobody's justifying his behavior, as you can see from his terrible reputation on this site.
@acidyo has taken the time to explain to you: everything posted on this site is posted into a blockchain, which is immutable and cannot ever be edited or redacted.
This means, in practice, that all humans, for all time, will be able to read everything posted here.
This also means that those same humans, for all time, will be able to respond however they wish. When you yell to 7 billion people, expect some of them to yell back. Expect many of them to yell back with things you don't like, things you would classify as "abuse", things you would classify as "illegal", "hate speech", "attacks", "bullying", et c.
There is no technical ability, under a blockchain architecture, for taking your public statements and making them accessible only to a limited subset of people. That's not how blockchain-based global consensus works.
If you don't want the entire world to be able to read what you have to write (and respond how they wish), then Steemit isn't the place for you.