Re: Hidan vs. Gai
Once gates enter the picture I don't imagine Hidan keeping up, he's canonically stated to have the slowest attacks in all of Akatsuki.
Gai in gates would dance circles around him, and Gai doesn't need to be that intelligent to decide he doesn't want to be cut but a giant scythe.
Eventually Gai's punches will leave him immobile. I find the whole Hidan continued on after breaking his femur argument rather poor. Even Part 1 Naruto fought in that state. But no one is saying that part 1 naruto is immune to physical damage. Take for instance, the rotator cup. Should someone destroy his rotator cup the arm attached becomes for all intensive purposes broken. Should the punch his kneecap out of place or destroy it all together his running ability is destroyed. In one's pelvis a small piece of cartilage that connects the hips, should that be knocked out of place by a punch walking would be nearly impossible.
Then 10 tons argument is quite valid considering the levels of strength we're starting to discuss. Having enough strength that the resulting wind pressure would be able to kill an ordinary person. You have to think of the force behind that punch. What's going on is the no limits fallacy but logically there must be a limit to how much damage he can take. I personally believe the top tier of those with physical strength all surpass those limits (Tsunade, Ay, Gai, Sakura, Third Raikage)
Finally the reason he can't be hurt by physical means is a sad argument is because the only thing that has ever hurt him has been physical attacks. You would consider the rope a physical object as well as his torture stick and so on. So if these physical objects can hurt him, and he doesn't even use impressive force with his torture stick to hurt himself, what makes people believe he is immune to physical damage. One could even think of chakra blades as physical damage as they take a physical form to accomplish their purpose. But regardless, he's not immune to physical damage, he's a masochist who enjoys pain and has great endurance. But considering how easily he's stabbed himself his durability is not as how as people make it out to be.