they appear to be selling it as part of a package with added mod, they cant sell dolphin as a script on its own, they cant sell it with mods stolen either,
Dolphin can be given away as long as you leave the copyright intact you can not sell dolphin sites unless you sell it with a minimum of 500 registered users and they have to be active.

you can sell dolphin as part of a hosting package, i.e. pay for the hosting account and i'll install Dolphin for you for free. you can pay for support or i see more can give that free too. but you are paying for the hosting, not the script

what they are doing is illegal