Quoting from that article:
> However, skilled immigrating workers can bring capabilities that are not available in the native workforce, for example in academic research or information technology. Additionally, immigrating workforces also create new jobs by expanding demand, thus creating more jobs, either directly by setting up businesses (therefore requiring local services or workers), or indirectly by raising consumption. As an example, a greater population that eats more groceries will increase demand from shops, which will therefore require additional shop staff.
If that's the "fallacy" then it's not much of a rebuttal. The UK has an immigration system that allows in quite easily the kind of people who do academic research and information technology. How that has any relevance to low paid workers in far more precarious professions (or no profession at all) who have to compete with low skilled immigrants who are unlikely to know their rights, thus pressuring conditions downwards, who are likely to find the low pay better than they could get back home (or worse, taking lower pay out of necessity because of their illegal immigration status) which again, pressures downwards the pay levels, you'll have to explain.
One of my friends is from a Baltic state and wasn't claiming for money she should've been paid, which suited her employer just fine (this story[1] turned up a week after I learned about this, about her industry and mirrored her situation) - do you think there was a reason my friend said all her colleagues were foreigners? I'll give you the two best reasons I think for that:
a) The company wanted to hire foreigners because it would be easier to scam them out of money and rights
b) Locals would be less inclined to put up with that kind of nonsense
How is any of this helpful to a country, the locals, or the immigrants?
[1] https://www.bbc.co.uk/news/uk-37350750