There is no logical reason why schools should not also teach biblical creationism alongside the theory of evolution in science classes.
Yes there is.
That logical reason is the fact that you're in a science class.
Creationism does not fit science at all. It is entirely based on belief/faith. It is not a part of science. People shouldn't try to put it alongside scientific theories like that.
Instead, you teach Creationism in a Religious Education, or a Philosophy class.
A class where you are taught that these are the beliefs of different religions/cultures. They are not science, because they are not scientifically backed up (a few people proposing ideas doesn't make it scientifically backed up, since the overwhelming majority of religious-believers believe what they do because of faith, not scientific reasoning. To some it's even a bad thing to try and scientifically provide reason for religious concepts, because it leads away from faith).
Now you can have people who are taught the scientific viewpoint. And they are also taught of the varying religious viewpoints (there's more than one).
But you're not teaching religious views as science, because they're not.
You can let students choose which they believe in (and believing is fine), but as part of education, they still have to
understand both scientific findings and religious belief. Anyone can understand both while adhering to just one of them, or even neither.
People can understand that the Scientific ideas are explained through scientific principles, such as empiricism.
And people can simultaneously understand that Religious ideas are explained through faith and religious text/tradition.
There's no need to not teach both. You simply don't teach just one of them.
And you make sure you identify them as being different. Students can choose by themselves if they want to place one on a higher level than the other.
