Helping other countries may be a good thing (although the Vietnamese government's human rights record isn't that great) but it doesn't offer a way out to current victims of forced labor, who can't just move to another country to benefit from the improved conditions there. Do you think they'd just get released once exploiting them becomes unprofitable? That would put a bunch of angry unemployed people on the streets, so the security services are unlikely to be in favor. The most likely path forward would be gradually transferring them into regular work, which works best if such work is available, i.e. there's no blanket ban making everything equally unprofitable.