Ok. So for your first point, WE DON'T KNOW IF HE CAN USE BM AND SM AT THE SAME TIME. And you wouldn't even know how that works, so you can't argue for it. Secondly, since BM lasts only 5 minutes, he doesn't have to catch Naruto, he just has to absorb the attacks and wait him out. Naruto can't switch between BM and SM, and he wouldn't be able to go into SM in this fight anyways, considering he has to be motionless to do so, and as far as we know, Ma and Pa would still be rejected. Nagato would kill him before he can go into SM, so the only options available to Naruto are KM and BM.
And you say BM will rip Nagato's head off? You realize it has CHAKRA arms? Which can be absorbed with PRETA PATH? BM is in reality no problem for Nagato.
Now, for your second point, firstly, Muu could have easily dodged Naruto's second attack. The reason he didn't was because he thought that his attack would hit first, and Naruto surprised him. If his aim from the start was to dodge it, he would have succeeded.
Now tell me where exactly BM shows speed superior to KM. From what I've seen in the mange, KM is faster. You can also see this in Bee's KM vs his BM. Bee is definitely faster in KM. So your claim there is wrong.
Your third point is irrelevant seeing as how Nagato won't let Naruto go into SM in the first place.
Finally, where in the world do you get the idea that Nagato isn't smart???? His strategy in his fight against Naruto was perfectly fine, and he would have won were he able to use Deva Path from the beginning. He was also smart enough to come up with his own idea for how to attain peace, something Naruto was unable to do. He is not stupid, and he would AT LEAST figure out that flying would pretty much solve his problems against Naruto. Thus, he would take flight, and Naruto would lose.