I have serious reservations about self-styled 'vigilantes', not so much for what could be argued is a public service - as would be a potential point of view in this instance - but for the slippery slope that lies ahead of such behaviour.
Without law, the vigilante attitude will always get out of hand, slowly or quickly, as self-righteousness clouds moral judgement.
As Dirty Harry memorably expressed it when discussing the vigilante police cadets in the film Magnum Force, "next thing you know, you execute your neighbour because his dog *** on your lawn ..." which had its finger on the pulse of the problem of vigilanteism as far back as 1973.
So no, I don't believe this is the right way to go about things, although I entirely understand the thinking behind the concept - if these are the new 'law makers', who advises them, who holds them accountable?
Where would we go from here?