2
1-st: "...You may not use this work for commercial purposes..." can't be used "in GPL context". I don't want start again long battle, thus, in short: "Free software doesn't mean always 'free of fee', only 'free as freedom'"
2-nd: Noted you statement is extraction from Creative Common Licence, under which licenced content of this site (except separately and specially mentioned parts) - text, image objects. NC-SA ("non-commercial share-alike") CC-licence allow free using licenced under which licence materials, if
- it used in non-profits areas
- credits and copyrigths of original author are untouched in used data and derivative work.
Creative Common Licence cover only site and haven't any relation to XOOPS, which licenced under GPL (and commercial usage of GPLed products aren't prohibited)