[league]

What TOS claim license and no reuse to this, which they can't. The distribution of the app through the App Store links to developer site. The Wix landing page (developer site) carries a link to Wix terms which state:

2.2. You undertake and agree NOT to: (caps mine) copy, modify, create derivative works of, download, adapt, reverse engineer, emulate, migrate to another service, translate, compile, decompile or disassemble the Wix Website, the Wix Services (or any part thereof), any Content offered by Wix or Third Party Services for use and display within User Websites (“Licensed Content”) and/or any part thereof in any way, or publicly display, perform, transmit or distribute any of the foregoing without Wix’s prior written and specific consent and/or as expressly permitted under the Wix Terms;

So they're claiming proprietary license to Wix Services and no reuse of work that contains WP code which they cannot under the terms of the GPL.