Evolution has been taught in public schools for decades. It's mostly presented as established truth. And yet, some 60% of the public does not believe in it. Imagine what that percentage would be if part of the teaching were to explore the views of scientists who have don't accept Evolution. There's quite a bit that can be said against it, and although you may not find this side of the argument compelling, can you imagine the outcome if schools truly presented both sides of the debate? The number of Americans who accept Evolution would likely be smaller, don't you think?
Perhaps that disturbs you. The folks who oppose Evolution are sometimes derisively compared to Flat Earthers. Let's look at that as one "alternative theory":
What if, for decades, all students studied Geography and that a central teaching of Geography was that the Earth was flat. Now, there is another side of the argument, and that side would also be taught. The teacher would show film from astronauts in space orbiting the Earth. Students might talk to people from Australia ("No, we're not standing on our head.") and reports could be done on traveling around the world via major airlines.
After decades of presenting both sides of this Flat Earth controversy -- how many Americans would believe that the earth was actually flat? I'd expect less than 5%.
So (my opinion): if we teach both sides of Evolution, the percentage of people who accept Evolution will go down. If we teach both side of Flat Earth Theory the percentage of Flat Earthers will go down.
Someone's pet theory is a lot like the Flat Earth theory. And it ain't mine.
My point: teaching both sides of alternate theories is only frightening to the people who want their theory accepted as a matter of faith but who lack the means to make a truly compelling case for their side.
Try re-reading my post 6. You seem to have missed the point. Or are you possibly presenting strawman arguments knowingly?