IANAL, but these guys are also not (but I think wix.com did consult them). The WordPress component in question is based MIT license which might not included in

IANAL, but these guys are also not (but I think wix.com did consult them). The WordPress component in question is based MIT license which might not included in valid way as GPL and Wix.com is using that component. I assume Wix.com's layers told them that this component cannot be protected under GPL so they are ok to use them.