1.Women in tech get used to a lot of criticism that has to do with appearance or how they present themselves and begin to assume that all criticism of this sort is exclusively because they're female.
If I am going to give someone honest and earnest criticism about a presentation, I am going to do the following, likely in this order:
All those three steps are important. You ALWAYS first complement the quality of the information being presented, you want to acknowledge the presenter's expertise and the work that went into preparing the presentation.
It sounds like the author of the article gets a lot of feedback that just consists of #3.
One of the other posters here actually made a good statement in regards to the hair twirling comment, the poster explained why it was a problem and gave some other non-gendered examples of other self-calming behaviors that presenters unconsciously do.
If I was giving that feedback, I'd say "I notice you have some unconscious habits that show you are nervous presenting, you'll make a stronger argument if you relax and avoid those types of gestures, though some of this just comes with practice." If I am asked what sort of behaviors those are then I'd give examples of things like brushing hair off one's face, men playing with their beard, or drumming one's fingers. If I'm asked for what specifically the presenter is doing then I'd give a precise example.
This is feedback for anyone though. Feedback, (especially in a public forum!!!) that starts off directly criticizing is feedback that seems to be attacking the other person. More so if the only feedback one receives about an entire tech talk is just about one's physical appearances!
(I have a particularly horrible habit of my ear itching and I end up having to scratch it, ugh!)