I get your concern but is it possible that your idea of confidence is shaped by a male perspective on how that trait manifests?

Encouraging a junior team member to have more self-assurance in their presentation style is one thing but routinely asking women to behave more like men is another. This same scenario could be seen either way depending on your perspective.

To address sexism in the industry we need to be able to have a reasonable conversation about these kinds of subtle and subjective differences. There are grey areas and we won't all agree but resenting the challenge to think this through is probably not a response that's going to affect change.