It's clear that he hasn't responded in the right way to people's criticisms. However I would say that if someone is flagging your posts regardless of content, it is entirely legitimate to comment on your own posts to draw down their voting power. That is a legitimate form of protest, as is trying to bring attention to the situation.

The fact that someone can do something, or has a right to do so as part of the platform, doesn't mean what they're doing isn't problematic or isn't bullying. Any behaviour that makes Steemit a poor experience and drives away users shouldn't be seen as acceptable. Even if you don't like the OP, the mere fact that it is so easy for a large stakeholder to bully other users makes the site/network unappealing to newcomers.