It could be argued that it's a self-defeating argument anyway, on trade at least: leaving the EU can be justified by arguing that we need the freedom to sign and arrange our own trade deals, but where is the urgency for that if there are currently no meaningful barriers to trade anyway?
The answer to that is pretty obvious, which is that NJ's claims about the current trading system are, at best, highly misleading.
As regards the Irish border, we've gone over this multiple times, so I can't be bothered to revisit the arguments in too much detail. Still, it's pretty obvious that nobody wants to be seen as *choosing* to impose a Hard Border, which is why all sides are currently arguing that they don't intend to. But at some point the best intentions will run up against legal and political reality. Neither side can preserve its customs integrity unless trade across the border is properly monitored.