I hate it, but they absolutely have the right. That's like saying "too bad Google thinks they have a right to my emails". They're up front about it, and you're perfectly free to a.) campaign to change their decision or b.) not use their product.
Maybe adverts on a website is more apt. A company is putting time and money into a product, and attempting to monetise it with advertising. As a user, you can chose "this level of advertising is fine by me" or "this is too much I don't want it", and then either stop using their product, or prevent the adverts from happening. And sure, I go to websites with popups and pop-unders and etc. etc. which make me think "what the hell are these assholes playing at", but I'd never question whether they have the right to do it on their own website, only whether I want to visit that website again in the future.
It's amazing how quickly we've forgotten about that...
For Ubuntu, a.) and b.). Shuttleworth's childish attitude is shocking.