There is no reason why they wouldn't open source it. The business case is purely in the domain name.
Discussion
a domain name/business name is no reason to not open source. do you have a link to where you heard this so i can read more?
The domain name and marketing is where they can make money, as the core tech is already open source anyways, is what I meant.
When you look closely at a business, there is usually no good reason to keep the source code hidden - the best reason is because you are doing something you don't want people to see.