The whole "liquid explosives" thing is a complete furphy from the get-go, so in real life there's no "security weakness" to "seal up".
However, assuming for a few minutes it wasn't, if the terr'ists can get at the duty free booze, then they can get at the softdrinks and other liquids on sale in the airport as well, far more easily. Unless you seriously want to argue the $5 bottles of water are handled and secured more (or even equally as) carefully than the $500 bottles of Scotch ?
Let's also not forget the liquids that some people will _absolutely_need_ to carry onboard with them, like medicines. Again, a trivial avenue of attack if we're prepared to entertain the whole "liquid explosives" idea.
Look, if you're anti-alcohol just come out and say it. Don't try and wrap your bias in these silly ideas that don't even stand up to a cursory analysis.