I think that decision is best left to the judge...
Does the person need to travel internationally to repay their legal debt, or are they looking to disappear off the face of the earth and not repay?
Does that person have a valid appeal in over the child support, or are they just stalling to avoid paying?
Bringing a life into this world is an awesome responsibility and with it comes obligation. I certainly hold a child support payment defaulter in considerably lower regard than someone who misses a credit card payment or two.
I guess the question is: Why should people who disregard their legal obligations be afforded the same privlidges (passports, drivers licenses, etc) than people who do the right thing? Maybe they should consider the consequences of their actions before going through with them. I pay my taxes and bills on time. Why does someone else get a free ride not to?