There's a button right there that says 'close'. I assume you just didn't see it. Granted, I'm not a fan of this either - but it's hardly holding the content hostage.
I never noticed the Close button before, so I tried it w/o the ?share=1 in another browser. I get "Close & Read First Answer". All the answers after the first were blurred. I think this is the first time I've seen a site A/B test how best to annoy people.