> the models being women has no impact on the subject

It's part of the context; design doesn't exist in isolation. Was this prototype aimed at women? Was it just sexism or its off-shoot 'sex sells'? Or were there actually male models, but the author isn't mentioning it?

I would also argue that explicitly ignoring the fact that these models were women amounts to erasure, which is probably not intended, but a consequence of doing this.

If we get back to how it was originally presented: https://www.expo70-park.jp/cause/expo/sanyo/

It was part of a world expo, and from the text we can see it was set as a futuristic vision targeted at anyone that could use the apparatus. The official description also has no focus on the models or who it should be used for in any specific detail.

I get your point on the models all being women, but as that has more to do to the period than the machine itself, it isn't remarkable in itself. It would be like commenting on the show guides being sexy women when discussing Mercedes' prototype at 90s cars. Pointing at the sexism and gender gap doesn't help the subject.