I'm not sure quite which body of theory or knowledge it draws on, but it certainly sounds convincing:
It’s not hard to make a case that the main flaw of the Remain campaign was in allowing the debate to be framed by the Leave camp. Framing isn’t a behavioural effect as such, but how something is framed provides the context for decision-making – and biases – to play.
Taking just one example, the Leave side managed to get ‘freedom of movement’ spoken about as though it’s a one-way street. And this is still true; listen to news pieces even today about the issue, and it’s all about EU citizens’ right to move to the UK, not about UK citizens being able to live in any of 28 countries, as a result of being EU citizens.
How could the campaign have been run to reframe this? I’ll offer just one example: loss aversion is good to tap into. For UK citizens like me and my family, the Leave campaign was about removing our right to live in 27 of those 28 countries. Expressing it more vividly, they want to take 95% of my/your passport away.