Were they actively making changes to the project and running custom builds? If not then they just had nothing to contribute to the project and there is certainly nothing to feel disgusted about.
If they want to give up the intangible benefits they would get from sharing those changes (at least the non-business-strategic ones), that's disheartening, but I wouldn't lose any sleep over it.
In my case, I started feeling like I was working for a parasite. And... I didn't particularly want to continue working for a parasite.