They suspended Antigua's and Barbuda's obligations to comply with US intellectual property rights because the USA did not comply with prior WTO rulings. [1] It is still illegal and essentially just a means of punishment. Copyright holders could probably try to sue the USA for not complying with the WTO rulings and in consequence causing damages to them. But honestly the whole case seems pretty ridiculous to me.

[1] https://www.wto.org/english/Tratop_e/dispu_e/cases_e/ds285_e...