He is probably using reports from the Centre For Immigration Studies. I believe they can be trusted to use real data, but can't really be trusted to represent it in proper context. I'm not sure if they cherry-pick cynically or just out of confirmation bias.
Shrugging and saying "confirmation bias works both ways" is neither factual nor a valid rebuttal. Confirmation bias is a value-neutral phenomenon. It is neither innate, unavoidable, nor inherent to sociopolitical analysis. It does not "work both ways." It works only one way.
There are numerous sources of policy opinion all across the political spectrum that exhibit confirmation bias. There are also those who attempt to limit their own bias and do scholarly policy work in good faith.
When a person or publishing entity exhibits a tendency to systematical devalue evidence that contradicts their assumptions, that is confirmation bias.