If it has always been that way, then yes, it means that none of the assets can be levied for child support.
However that does not mean that he can't be put through the ringer, lose his license, and maybe even go to jail for non payment of whatever a court has ordered or will order him to pay.
If you are faced with a husband in jail unless a purge amount is paid, what are you going to do? If you are faced with never being able to face married life with your husband's income/credit being able to contribute towards your family's way of life, what are you going to do? If your children can't get student loans for college because their father has defaulted on CS and has a horrible credit score what are you going to do? If you can't take a family dream vacation to Europe because your husband can't get a passport what are you going to do? If your husband's social security retirement benefits are being garnished due to unpaid child support from many years in the past what are you going to do?
The point I am making is that is simply not as simple as whether or not you have to pay for his child support. Its what will your combined FAMILY have to eventually pay if he doesn't support his other children?
If you make a good income and can support yourself, him, and any children that come along from your marriage, great,...but at a minimum you should be pushing him out the door to be earning enough to at least support his other children. That would be in the best interest of YOUR marriage.