You don't think that if he wanted to but was genuinely unable to move his body, he wouldn't have commented on that? You guys are reaction scaling too much. Shanks will never ever show the ability to stun anybody above vet level post-Wano, be sure of it.
1.) Greenbull could move during that attack, but it's still painful for him and Shanks can keep using it for a while
2.) Greenbull cannot move during that attack, but it requires immense CoC for Shanks to use and he can only do it for a few seconds.
The second option feels more realistic to me. As powerful as Shanks CoC is, it is hardly strong enough to keep a top-tier stunned for more than a few seconds at best. This feels in line with how Oda usually handles hax abilities, he makes it powerful but adds a time limit or bodily limit







