Judicial conservatives as activist judges

In an obituary to Ronald Dworkin in The Guardian (Ronald Dworkin: a modern-day Mill ) I was struck by one point:

Dworkin was ranged against those who conceive the judge as neutral referee with a rulebook – tasked with mechanically imposing the law. The problem with so-called black-letter law is that there are not enough letters to deal with the complexities that statute must govern.

America's judicial conservatives seek to resolve ambiguities by imagining their way into the constitutional convention of 1787, but in presuming to know what Madison or Hamilton might have thought about stemcell research or internet regulation, they afford as much leeway to their own whims as any activist judge. Dworkin's twist on the argument is that laws are bound up with moral ideas; we can't hope to make sense of 18th-century notions of liberty or cruelly unusual punishments without moral interpretation.

The stipulation that we should look to the original intent of our founders has always seemed rather silly to me personally.  I mean do those who seek original intent of the founders argue that medical Doctors should bleed their patients, or say, apply leeches where appropriate?  While I'll admit fundamental principles resonate throughout human history I'm not sure all aspects of the past should be venerated--in fact some things in our past supported by our Found Fathers should be nothing short of detested and vilified.. 

But if one is arguing we should seek the original intent of our founders on modern topics that our Founding Fathers couldn't have possibly thought of due to their nonexistence at the time we are actually seeking to provide ourselves with the leeway to create whatever interpretation our heart desires--which in many ways is the epitome of a conservatives definition of those killjoy "activist judges."