Dad in debt, no assets + social security. Options?

We recently ran my dad’s credit report and found that he has about $15k worth of debt. This balance is largely small loans/credit card limits built up over time then he consolidated this debt at high rates. Vicious cycle.

$5k of his debt is a mix of “placed for collections” and “charged off”, my understanding of this is that the creditor has written off this debt and may/may not have sold the debt to a collection agency. There’s $8k that was an installment loan where he received a cash lump sum to pay off historical debt (30%+ interest rate)… balance of $2k is still accruing interest and he is making minimum payments.

My parents live in Texas. My dad is retired, nearing 70 and his only income is social security. My mom is in her mid-60s and still in the workforce. They don’t have any joint accounts, the house they live in is under my mom’s name and has maybe $50k left on it. All vehicles are under my mom’s name. She has a 800+ credit score vs my dad being on the opposite end. My mom has some savings, a 401k that’s earmarked for both of their retirement vs my dad has nothing. My mom makes a very modest income and cannot afford to pay this debt down. She’s meticulous about saving money for retirement, paying down debts, and living within her means. She’s the rock that has planned out my parents’ lives financially.

Trying to figure out next steps. We plan on sitting my dad down and explaining that we’re going to start monitoring his credit reports regularly, and he has to stop borrowing money. May be unethical… but he has no assets and my parents’ finances are split, can he ignore his debt payments? My understanding is that debt collectors cannot garnish from social security income… so he may go to court and lose, but once they see that his only income is social security, he’s in the clear? He has no use for a good credit score. Can they go after my mom? Short of my paying off his $15k debt, just trying to figure out our options.

Thanks!!