To my understanding he was frustrated with the team before Bob McNair died. He was pretty racist and Watson is, you know, black. Things got a lot worse after he died. His wife, Janice, is the sole owner and let's her son, Cal, run things. They really have no idea what they are doing and before Watson resigned they discussed his involvement in the next GM/coach. After not being co tasted about either he know he couldn't trust them.
One of my buddies who is a Texan fan said the saddest thing ever. He said any coach or GM willing to take the job is such a loser that he immediately feels they will just be more of the problem. That perfectly defines 'toxic'. Essentially if the team touches it, it's ruined.