They're not wrong in that people often rationalize their 'instinctual' choices, but to imply that nobody is cognizant of any of their thoughts or biases and that we're all slaves to our lizard brains is a bit of a stretch.This is a massive false dichtomy.
On the one hand is people are biased in ways they aren't aware of, and aren't in control of their lives. And therefore are slaves to genes.
On the other hand is, since people aren't animal slaves, people aren't super biased, super unaware of their biases, and so on.
I think the truth is pretty straightfoward here: people are hugely biased, unaware of it, and bad at controlling their lives. But it doesn't mean they are slaves. They could do something about it. But evading and dismissing the issue, or accepting that's how people are, won't fix it.
Control over your life is possible but not automatic. It shouldn't be treated as either both possible and automatic, or neither. That's the false dichtomy again.
What will fix this problem is philosophy. Read Ayn Rand and Karl Popper, among others. Or come discuss this matter at the Fallible Ideas Discussion Group. Learn better ideas and integrate them into your life so you actually live by them.
The problem of bias (and more generally mistakes) is real, but also solvable. You don't have to choose from a false dichotomy of denying the problem exists (or downplaying it heavily) or else accepting the problem as a negative feature of human life. You can recognize the problem exists and then take steps to deal with it. A lot is actually known about how to handle this, but most people don't bother learning it.