It was a calculated risk that had a handsome payoff, if it worked, which is why it had to be open source, anything short of open source and Android would never have taken off like it did with several handset manufacturers via the OHA [0].
Remember, the context surrounding the need for Android to use an open source model at launch was that they were the underdog, iOS was still nascent but steadily gaining serious market share. The incumbents -- whom Google was hoping to disrupt using the OHA as a trojan horse was Nokia (they enjoyed 73% market share [1] with their Symbian "smartphone" OS) and Blackberry. Nokia would eventually start the process to make Symbian fully open source in 2008 [2], so they could compete better against the OHA [3], but the process didn't complete until 2010[4], which by then was already too late.
IOW, making Android open source was a core part of Google's strategic play to gain market share, there is no point in crying uncle.
[0] https://en.wikipedia.org/wiki/Open_Handset_Alliance
[1] https://en.wikipedia.org/wiki/Symbian#Market_share_and_compe...
[2] https://techcrunch.com/2008/06/24/symbian-goes-open-source-c...
[3] https://en.wikipedia.org/wiki/Symbian_Foundation
[4] https://www.wired.com/2010/02/symbian-operating-system-now-o...