In which case he isn't just pissing about with soft brexiters and the EU, he's lying to the electorate.
No, I think he does think it is essentially a small point in a greater good. But he is using it to his side's advantage here. It triggers people arguing that the salmonella rate is significantly lower in the US, and wondering about a ban that is used to stop people doing something that would be banned anyway (I.e. selling of chicken outside a legal time).
In some ways it's quite clever, in that I have already seen people 'challenging' Liam to eat a chicken in the US which he then will quite happily do, and say 'Mmmm' in screen. Much as people might hope for a Game of Thrones purple wedding moment when Liam chokes on the chicken in a Joffrey like expiration, it won't happen.
As I stated in my reply, I am defending Liam on the charge of lack of knowledge, not as a shimmering example of the vest of humanity.