He actually sounded as if he wasn't eager to have Rupp run a marathon too soon and saw his own experience as a "cautionary tale."
From what I've read (and I admit that's a more distant perspective than knowing the man up close), he does strike me as pretty intense and driven, but also aware through experience of the need for balance. And he also (again this is from a distance, not knowing him) seems to be someone his athletes will gravitate toward, someone with the kind of magnetism that will bring people into his influence.
Every personality trait has the potential to benefit or harm--someone very intense could help an athlete reach her potential or risk driving the athlete to burn-out if they're not careful. And someone more laid back might have the reverse situation: an athlete might be more comfortable w/ that person, but also not feel the push to achieve as much. All a balancing act, and Salazar seems to be aware of that himself, talking about the need to sometimes take a day off and not redline everything, as he once did.