Uggh. Sorry, I don’t mean to be a prick but it frustrates me to see you giving bad advice to someone who might not know better than to listen to you.
Yes he should pay off his credit cards. They’re probably, what, >15%? >20%? Invested well he might be able to make 8% in the stock market without having to risk losing it all and being doubly fucked, which he cannot afford to do if he has high interest revolving debt.
As for dying with debt, if you don’t plan and act in a way that will give you a positive net worth by the time you die then you’re going to be living off of social security (if it exists) in your old age. Not how I want to spend my retirement.
Taking a private loan for a car so he can acquire equity and get a loan: You mentioned a house. A couple-thousand-dollar car won’t mean anything on a mortgage application. As for using it to get another loan and start building credit, why not cut out that first step and go straight to a real loan that will immediately build credit history?