This is flawed perception right here. It's not about traits, but it's about the motivational structure where 8w9 is more likely to use sloth as a numbing mechanic. Not sure why you think enneagram is about behavior. It isn't.it's an 8 but it also has 9 traits
NOTE: After testing for my tri-type (last one I'm not sure about yet: 4w3), I think Entropic nailed it: sloth as a coping mechanism for the conflict: I use it, off-and-on, but now I am working directly, consciously, to grow, get psychologically healthy, work out this stymie effect.