As a native English speaker, I've always been under the impression that "asinine" has a connotation of willful ignorance, or arrogance, on the part of the person so described.
For instance, some of the things Donald Trump does I might describe as "asinine", whereas I would not use this word to describe a mentally handicapped person's inability to figure out something simple, or an otherwise reasonable person's honest thoughtless mistake.
However, it's not a word I hear all that often, and I've been known to have picked up the occasional piece of idiosyncratically corrupt English, so I decided to check on-line dictionaries, and neither of those I checked were too clear about this connotation.
- foolish, unintelligent, or silly; stupid
It is surprising that supposedly intelligent people can make such asinine statements.
- of or like an ass
asinine obstinacy; asinine features.
The example in 1. does hint at voluntary stupidity but is subject to interpretation (maybe they're actually not intelligent people), and it doesn't strongly suggest arrogance.
The first example in 2. is more interesting in that it invokes obstinacy, which is in some ways similar to what I'm thinking of. But the target word is used as a modifier of the word "obstinacy", so unless it's a tautology, it doesn't mean that the word "asinine" itself implies obstinacy.
The Collins at the same site does get closer in 1. (so maybe it's a British connotation?):
obstinate or stupid
resembling an ass
- Very foolish; failing to exercise intelligence or judgment or rationality.
- 1922, Michael Arlen, “2/2/2”, in “Piracy”: A Romantic Chronicle of These Days:
They danced on silently, softly. Their feet played tricks to the beat of the tireless measure, that exquisitely asinine blare which is England's punishment for having lost America.
- Of, pertaining to, or characteristic of donkeys.
There is some suggestion of willfulness in 1. in the use of the phrase "failing to exercise". But then, the quote, while fascinating, is also rather confusing since I'm not aware of the total context.
So I have a general sense that my belief could be at least partially true, but the evidence is equivocal.