First of all, only black people were chattel slaves in the Americas e.g. they "served" for life and passed down that status to their children. Indentured service, which ended after a term of years, could not passed own and was not slavery.
Having said that, I agree that coerced labor, such as indentured service, has much in common with chattel slavery. The poster, however, was not making that argument. He or she seems to have been claiming that working for wages was akin to slavery.