There's N options for optimal action, some more in category of "asshole", some more in "non-asshole".
Blanket statement all "asshole" actions are non-optimal is a pretty huge leap of faith.
The real question you should be asking yourself is optimal for what? Your statement (or sentiment at the very least) says you're optimizing for not being an "asshole", in which case, you're correct. That's also the only case where you're fully correct.
His argument is that success does not hinge on being an asshole - and that one can accomplish one's goals without being an asshole.
There's nothing in there about optimality or minmaxing every one of your decisions.
Whatever your goals may be - unseating a corrupt taxi monopoly, organizing the world's information, whatever - OP's notion is that it can be achieved without being an asshole.
His statement wasn't "all asshole actions are non-optimal", and frankly given that optimality wasn't even hinted at in his post I have to wonder where you're getting it from.
In my book, it's simple - if I have a maxim "do not be an asshole", then I won't be. If I do not, but instead "unseat a corrupt taxi monopoly", then I'm bound to be an asshole in some of my actions. If I have both, they're bound to clash in some subset - there's no synergy of limitations.
And, like my thread sibling stated, paraphrased, you're bound to be marked an asshole by some anyways, whether you're Gandhi or Zuckerberg.