It's a lame argument that just because an evil company like Google or Facebook or Microsoft made an open source product that you are using, you need to shut up and stop criticising them!
The fact that someone uses their open source product is an endorsement to the open source movement, not of the company.
The fact that a public for-profit corporate made a product open source doesn't mean that they have suddenly become altruistic - it just means that it made business sense for them to make it so.
The fact that it is open source means that the company doesn't own the product nor can it control you. And the fact that it is open source means that the product is being made by contributions from the general public too, and not just the company.