Don't shift your loss back "formula" nondisclosure to "behavior", upon asked for their formula this casino refused to give it. It's quite low though, about 5 % monthly on cashback, where on most casinos you have 10 % weekly. This is where their "threats" of account termination started.
You should move on from the casino if you don't like their bonuses. I have played at a different casino where they give only 2% of the house edge as weekly bonus and 3% of the HE as monthly bonus. Your behaviour was indeed aggressive with their support agent.
Honestly speaking, terminating the account is the last thing the site wants to do, unless left with no other choice.
I don't know the whole story though, but I think 500 Casino team should have kept his account active for playing with deposits and bonuses. The user said that he has wagered more than $1.8 million at 500 Casino. This is a good wagered amount if the user is an average gambler. Maybe there are more casinos with similar terms, but I haven't seen this type of complaints before.