That's a nice idea that if we'd just agree to politely look the other way or be generous about letting the word woman and female be used by any male who wants to that would be the end of all the issues. I don't think that is the actual issue at all.
The issue is the demand, and it is a demand, that all males who choose to so self identity have the exact same right to be in all spaces designated for female single sex provision, and that the mixed sex term woman should replace any ability for female humans to name themselves as a sex class, or to have provision reserved for them that is single sex.
This mixed sex at all times definition of women then leads to:
female people not able to go to a refuge because their trauma and PTSD or their faith or culture or disability makes it impossible to live in a building with male people
female people having to avoid health care or discharge themselves from hospital wards if it is impossible for them to be alongside male people in a state of undress or receive intimate care from a male
female people unable to go into female toilets in public places because they are not able to go into spaces to undress and toilet where male people are - which restricts them from access to public spaces, and many of the females who would be most affected would come from groups already not easily accessing public spaces
female people unable to use the female only swim times or yoga times etc set aside for females who could only access swimming when male people weren't present - and now can't use them any more because male people are now present.
female children staying off school when they have periods and not drinking all day because they cannot have a toilet space where male children aren't present
I could go on and on. It goes much, much deeper than just being kind about language, there are huge issues of equality and access here for females that can't just be put under the carpet.