There's absolutely nothing in the "idea of Open Source" that suggests upstream has to accept contributions. Open Source allows you to tinker with the code, not force your changes on others.
Equally you are welcome to not sign anything you font want to sign. There are reasons for those docs, there are reasons to not sign them. It's completely your choice.
And of course you are free to fork anything anytime you like. You're even free to encourage others. So no beef there.
I presume you have at least followed your in principles here? I'm guessing you have forked Linux, and your browser, and your favorite language? And office suite? Posting links here would likely attract others who object to corporate development joining you.
