Probably this: "He was the type of engineer who tried to dominate technical discussions by insulting and dismissing others rather than by demonstrating the merit of his ideas. Most engineers would just avoid the confrontation and this allowed him to railroad bad ideas through."

I have seen this play out multiple times - acting like asshole can make you look smarter then you are and smarter then nicer people.

First, he ended up dominating discussions, so other peoples ideas were not told. This is simple, he is having ideas and they seemingly don't.

Second, other people got criticized a lot and he did not got criticized. Hence, others looking like having bad ideas and him looking like having good ideas. Yes, criticism was actually insults and dismiss and actually actual arguments, but it unfortunately often does not matter when people make impressions.

Third, people have tendency to buffer criticism with praise. So when they criticize him for having been asshole, they will first euphemise with "low social skills" and then add something like "but he is good programmer/professional" to it. So that they dont sound biased or overly negative. Unfortunately, they rarely buffer praise with praise "he is so nice" is rarely followed with "and also good programmer" cause it feels unnecessary.

It does not work that way for every kind of asshole through, not everyone can achieve the same. But when it works this way, imo, above are factors.