If you have a legal team making a good enough contract and the buyers legal team is not good enough to catch it. There should be no problem at all.... There is absolutely nothing to stop you from selling your business with a clause like "You pay me a shitload of money but I keep all the business rights" if the buyer is ignorant to sign that deal.
All I can say to eBay is.... Next time get a better legal team :-) This time... just suck it up
Mind you this hammers in all the pro's of IP-laws and software patents and all the terrible thing associated with open source :-D