Interesting, that's the first time I've heard that about Bernstein. It's definitely not an impression one would easily get by watching the Young People's Concerts, for instance.
For salty demeanors, I've heard anecdotally that Stokowski could be pretty rough.
When I think of more endearing reputations, I suppose I think of Solti.
Still, I'll take Bernstein's body of work over Barenboim's!