That article doesn't say much about the bill itself, but I gather that one section of it says that you must use the bathroom on your birth certificate. I agree with that.
For one thing, it's ridiculous to use the bathroom for which you are not equipped. Men's and women's bathrooms are designed differently for a reason. Now, it might not be a huge sanitary issue for a woman to use a men's room, but it certainly is for men in women's restrooms. Men pee in toilets and it does splash up and go both onto the rim (or the seat if it's down) and the floor. Not a huge issue in a home bathroom, but I sure don't want to sit on a toilet seat that some strange guy just peed at. Even if he did put the seat up he either used his foot, eww, or he used his hand, which he then touched the lock with, which I then had to touch before I used the toilet, also very eww.
And then there's the issue of some pervert just claiming to be an opposite gender identity so they can use the other bathroom. It's already a thing that happens that some people will be arrested for harassing or trying to take pictures of or goggling at adults or children in their assigned bathroom. It's not like it doesn't already happen. There's no reason to help make it worse by making the other bathroom more accessible to people like that.
There's also the argument that being convinced you are of a different gender is often part of a larger issue of just being unhappy with your life and trying to find an answer. And gender change is not always the answer, but most psychologists are so afraid of being dubbed bigots that they don't try to help these people find out what is really bothering them and help them, they just give them what they say they want and recommend them for gender reassignment. There has been very little follow up done on people who change gender, to see if it does help them. In fact, there has been one long term study done in Sweden,
and it may be the only one. It found that the incidence of suicide and death in general when compared with a control group as closely matched to the study group as possible was very high. So were crime, psychiatric problems, and several other things suggesting that these people are definitely
not better off changing genders. It's just as bigoted to say that someone who thinks they are the wrong gender is not mentally ill as it is to say that they are and I think allowing them to use the wrong bathrooms is only helping exacerbate the problem.