No it's not. I believe all license terms are clear about that - images can not be made available or download.
I even remember having read in one of these agreements that images on websites should not be larger than a certain size, even if the buyer purchased it in a larger size. I guess this is exactly not to allow the use of a high res image simply because a true buyer used it in high res.
BTW, through TinEye I also found one of my images in such a site, but in this case it was a DT thumbnail. I reported to DT and later these images were not at this site anymore. It was strange that this site announced them as "free desktop wallpapers", but all you had access to were thumbs. The site had a log on area however, so maybe members had access to full-size images.
Regards,
Adelaide