That doesn't necessarily prove anything. Google and Apple were partners before Android.
Google Ventures independent from Google (and goes through pains to point this out when you pitch them). While there is obviously a lot of synergy, Google Ventures employees are not Google employees, and do have not have Google stock options.
Also, if you want to look back through the annals of tech history, many larger companies partner with disrupters when a new technology emerges, only to enter the market when the new technology grows into a significant market.
Google Ventures invested $258M in Uber in 2013 and are one of it's largest shareholders.