This could actually spark a interesting topic on the GPL Licensing. I would suggest annyone that wishes to engage in a particular argument based on the license, to read the following page:
As far as material that is being received through wpmudev premium which is not under the GPL license should not be able to be sold for profit, afaik. Dutchmall does mention it resells both to the public for support of the site, which I agree is wrong, depending on the license off course.
It does indeed mention that the fee is not for the theme or the product and that all materials are created by others, but how can you charge a fee for a theme or a plugin before downloading, while at the same time state it is not for the plugin or theme? No allegation, but surely confused.
I could not find a clear ToS on wpmudev which clarifies this violation, so it is hard to say what exactly is allowed or not and what other licenses are distributed apart fomr the GPL.
Considering the GPL it is actually astonishing not more plugins and themes from wpmudev premium are not readily available by others providers as that seems completely legal. I am not a member of wpmudev premium, so again, I don’t know what the ToS is or licensing beyond GPL.