I don't think he's using because he's huge and conditioned.
I think he's using because he's huge and conditioned and old, became substantially huge-er, in the span of a year or two, after looking more or less static, and already being very very well acquainted with diet and training. It's a matter of a sudden leap forward in his 40s.
It's not about his physique considered in a vacuum. It's about everything taken in context.