Why did Google wait ten days before notifying OpenSSL? (even if they didn't trust OpenSSL to handle it responsibly, it couldn't have taken ten days for Google to patch their systems)

... to give preferential treatment.

Given that the entire world is already divided between people who believe the conspiracy theories circulating about Google and people who love Google unconditionally, I doubt they really care too much about appearances -- people are going to think whatever they want.

More likely this is to keep them out of court.