Earlier quoted context omitted.
The GP thinks its about "getting even", as if China and India were naive, noble backwaters the devious Europeans pulled the wool over and secretly exploited in 1700s. When really, they got out competed in trade and on the battlefield by the Europeans.
So, it’s fair if a European gets out competed in the labor market today.
So it's equally as fair for those laborers (voters) to say "no more importing cheap competition". The UK already has. It's incredibly difficult to bring in foreign employees.
Edit, addendum, ignore the part about companies, though you'd said European firms.