It's certainly commendable that Slate is taking as strong a stand as it is on vaccination. The problem is overall pandering: the well-meaning science columnists there like Phil Plait would probably like to take a similar stand against the wall of anti-science, anti-engineering prejudice that has dominated the left since the Seventies, but are afraid of pissing off what the site sees as an important segment of the readership. It almost seems as though they're hoping that taking a strong stand on that one issue will gently remind readers that perhaps they need to rethink other topics in science.
A prime example of 'Slateism': on climate change, Slate's columnists not only demand that we accept the most apocalyptic interpretation of the data as gospel (scientists are not used to using terms like 'believe' and 'denier', but okay, the Maoists take taken over the issue), but that we automatically reject every proposed solution. We're all going to die, because that's the just fate Gaia intends for us as punishment for being fat and eating meat. We can't go nuclear to eliminate carbon! We can't bioengineer better crops! We can't geoengineer for carbon control, even by doing something as mild and self-limiting as seeding deep ocean waters with iron sulfide to promote algal blooms. Even the new California solar plant attracted its own firestorm of opposition.
I have no interest in political conversion here. Left and right are different cultures, each with its own set of values evolved over generations. What I would really like to see is a leftist site that reclaims the spirit of Roosevelt. If we have problems like climate change, energy shortage, war and poverty, let's attack them by building the giant public infrastructure projects that Steinbeck waxed so lyrical about. An energy independence Apollo would address all of these problems at once.