It's not just a dodge, although considering the user saying it has repeatedly considered me disingenuous, it's worth a laugh.That's just a dodge.
It's just a different perspective entirely. Some things are true because they are a fact of reality, other things are true because people decide them to be. If someone sees gender purely as a social construct, that gender means whatever people agree it means, then "I am my gender because I feel I am" is a acceptable standard. There's no science or reason behind it, nor does there need to be, nor does that make the statement any less true. Like, going up a level of analysis, "gender" is a word. All words are social constructs (outside of maybe onomatopoeias), words mean whatever people agree they do. Gender can mean whatever we want it to, and if gender the social construct wins out, so be it. There's no sense asking there what the rules are, because there doesn't need to be rules if people don't want them.
Now, if someone expresses the idea that people are the gender they say they are without question, and then they try to establish natural rules for who is what and why, or try and support their position with scientific studies, that person is being self-contradicting. If someone insists something like "trans men are really men and here's the brain scans to prove it", they no longer get to act like there is no standard, having publicly accepted a standard themselves.