Funny that Google requires employees to say "THIS IS NOT A GOOGLE PROJECT, THIS IS MY 20% PROJECT", yet reserves the right to say "I can have this" at any point.
The first one is a warranty issue. The second one is a work-for-hire-copyright-law issue.
Well, Google literally paid the salary of the developer while he was developing it. This isn't even like it was something done on his personal time that Google can stake ownership in since he works there. It literally is a work product, which just happens to be not supported by Google.