President Trump is right. Sex is binary and immutable.
Congress needs to codify the President's executive order into law.
President Trump is correct that there are two sexes, and that sex is an immutable characteristic. Sex is never "assigned" at birth. It is simply recognized by observing the baby's anatomy and can be further confirmed by genetic testing. The same people who have demanded that we "follow the science" regarding COVID-19 are science deniers when it comes to human biology. I was both surprised and pleased that this was done on President Trump's very first day in office.
Leftists have wailed that President Trump is seeking to put "trans women" in men's prisons, but the fact is that there are many documented cases of "women" with intact male genitals raping women in prisons. (I wrote about this here and here, and your favorite search engine can turn up much more.) While "trans women" (also known as men) do indeed need to be protected in prison, that does not justify violating the privacy of biological women in prison, and it certainly does not justify subjecting them to being raped.
Politically, this is a smart move. Americans of both parties broadly agree with Trump on this issue. They are horrified by putting female prisoners in danger of rape. They are opposed to the "cancel culture" mob swarming people who recognize biological reality. They understand it is unfair for someone born a man to compete with women, as men have greater bone density, muscle mass and lung capacity. President Obama and President Biden did everything they could to eviscerate women's sports, and Trump is reversing that.
But while I appreciate President Trump's executive order defining only two sexes and recognizing that they are immutable for the purpose of enforcing federal law, this could easily be reversed on January 20, 2029 if a Democrat wins the next election. In fact, the executive order is probably already written, waiting for the next Democratic President to sign it. This is why Congress needs to work to enshrine this in federal law. It is much more difficult to overturn a law than an executive order.
In fact, this is a symptom of a much larger problem with our federal government. Congress was envisioned as the most powerful branch of government, but Congress has become the vestigial organ of American government. Congress has ceded authority to the bureaucracy to write "rules" with the force of law and failed to stand up as President of both parties have gobbled up authority for the executive branch that rightly belongs to the legislative branch. If we truly want to restore constitutional governance, we need to reverse that trend.