This quotation doesn’t comport with Jefferson’s ideas of strict construction of the Constitution, either, unless this quotation means simply that while Jefferson doesn’t believe in frequently changing laws and constitutions, he isn’t averse to changing them as time and experience reveal deficiencies therein. But changing them how? By viewing the Constitution as a “living” thing that somehow organically changes with time, public opinion and judicial whim? I doubt that Jefferson meant this, if he indeed said what is quoted above. But the Constitution already has a process for its amendment, without the need to resort to all this “living document” stuff, and that process has been used for this very purpose: see the Twelfth Amendment.
The real question, it seems to me, is, would Jefferson, if he were alive today, want to amend the Constitution to repeal the Second Amendment? That’s pretty much unknowable, though I personally doubt he would. And as Dr. Gutzman says, Jefferson seems to have been pretty supportive of the right of citizens to keep and bear arms.