Aye that’s part of what I was saying. Now, the argument could be made that if the octopus is smart enough to have the goal of moving through the tract, they could muscle open the sphincter. I haven’t ever tested an octopus against a sphincter. The controlled variable would have to be octopus size…

Off hand, I think the sphincter would win out until the octopus is too big to fit through without rupturing other areas.