I think there's nothing wrong to do that, but deleting people posts for a sake of own satisfy is childish.
I disagree, not childish but evil.
He is deleting conversations where he was accused to be a plagiarist and the conversations where he insulted others badly. He removes it to hide his trace so that it does not effect his DT position, I can not think any other reason for it.
trying to build a reputation here.
People build their reputation here, gives their time maybe for the love for Bitcoin or maybe to have a business f their own. Everyone works on building their reputation but when someone is obsessed with their reputation and using the hole of the system to achieve it then their motive become questionable. Since they are not honest, trusting them with anything can be risky.
No doubt he study the wholes and use the wholes in his favor to fool moderators, to fools everyone else.