> So he's very clearly biased toward proving minimum wage increase's success.

You may not have meant it this way, but that sentence implies you have already dismissed any point he makes purely based on what he believes in. Without any evidence, you've implied that any conclusions the author makes are automatically devalued because he will be incapable to undertaking objective research.

Would you write a similar sentence about say a medical researcher? 'Researcher is a member of the medical industry and is very clearly biased toward proving vaccines are safe and necessary'.

(Note: I think it's very important to be aware of influences and biases in hearing opinions - an important part of critical evaluation. Your comment does that for the most part ... it's just the last sentence I have an objection to)