Melt the murderous thugs? No need to waste so much energy. Just fry 'em.
Ignoring, for a moment, the obvious fact that STC's "solution" is absurdly impossible, is he going to then melt murderers' and terrorists' knives, bats, pipes, & other clubs, trucks & cars, and .....?
Use a little smarts! Forget going after tools that are useful to law-abiding people and go after the people who do not abide by the law. Increase the risk in and reduce the pay-off for crime and it won't take long for crime to plummet.