Well at the very least it will make life harder for bigots.
Seriously, this isn't about the fact that Eich donated to Prop 8 5 years ago, it's that he seems to still hold this position. He has had ample time to offer an apology( in a sort of "facts change" manner) and the fact that he hasn't makes the case that he still believes in oppressing homosexuals pretty strong.
Free speech is not consequence-free speech, and he's still able to say what he wants. But expecting people to ignore who he is when he's representing one of the most symbolic companies in the open source communities is unrealistic.
Why would any of us want someone with those social views representing the tech community at large (especially at a time where so many -ism's have shown themselves to be prevalent). If he just wanted to do tech, maybe he should have stayed CTO.