One would imagine it's the same lens they looked through when deciding that remaining in the EU would be the best course of action. There are various things in life that are probably quite personal, yet one would hope you have a degree of evidence to back them up, whether through personal experience, external evidence, or both. It's hard to imagine someone who thought an open, tolerant and outward looking country that was a willing participant in international bodies is going to change their mind after a referendum that has prompted the government to hit out at migrants, paint the EU as enemies whose governance we should obstruct if given the chance, and offer no real vision or strategy for anything else.
Had a Brexiter come out and said we will leave the EU because we want to be even more open, to participate even more in the international rules-based order of things, and so on, then that gives liberal voices in parliament something to hang their hat on. Instead, we've got the ERG tail wagging the dog in an extremely illiberal (and often illiterate) direction.
