Ok so he basically made a hidden javascript based miner and tools to distribute it.
Couldn't find anything to support the claim that he would have tried to dox Krebs. Also "maintaining biggest ransomware crypto coin network" feels like a dishonest phrasing trying to make it sound like he had something to do with ransomware. Monero was practically never used for ransomware payments back when coinhive was active, and even today Bitcoin is the most used method for ransom payments by far. Monero was simply the most profitable coin to mine with CPU.
That being said I agree that I wouldn't trust any software made by this guy. Even the hidden miner was obviously highly unethical and probably illegal.