Ahh the old "We've partnered with one of the largest proprietary software developers in the world to somehow improve open source things" trope never gets old.
So partnering with Google on Open Source can make a lot of sense.
But it's in vogue to hate everything Google does on HN at the moment, so oh well.
Company XYZ is the largest developer of proprietary software
Company XYZ is the largest contributor to open source
If we're talking about raw amounts, not %-of-company's-output
"if google is largest proprietary software developer, which company is not?"
is "all the other ones".
I promise I'm not being purposefully obtuse, I really can't find any other meaning to that comment.
I really don't know how Google "ranks" w.r.t OSS contributions.