Quoting myself to say I don't think Alice has autism, but I'm not an expert on it.
I think her behavioural tics and strange body language are things she's picked up over the last few years. Maybe from spending most of her time inside the house, arguing with people on the internet, and not interacting with many people in real life.
I know we frequently cite this interview with Alice from French TV from the 90s, but it shows someone who is behaving perfectly according to social norms. The difference between here and the video from her con is that she is the centre of attention. She knows everyone in the studio is hanging onto her words, and she's also flirty and charming.
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I totally agree with you that she if off kilter in everything she does - her fashion sense; her handbags; her anecdotes about being a perfect mother with perfect kids and how they all love each other the most and never fight; and the entire way in which she's handled this divorce.