While it's all well and good to create a third option for legacy-style avatar shapes that meet this non-binary avatar need, the Senra mesh bodies are similarly 'very binary'.
In trying different shapes while using the Senra bodies, certain sex-specific 'secondary sex characteristics' (breasts, pecs, larger butt, large feet?, etc) seem to be non-changeable on the existing Senra Bodies.
It seems only reasonable therefore, that a third, more 'androgynous' body type be offered as well. Something with more lithe features, with the ability to have a flatter chest than Jamie, smaller feet than Blake, and more control over butt size either way.
Non-binary and gender non-conforming representation is important, and in a world where we can 'be anything we want to' such as Second Life, it almost seems essential.
This may also be a good companion to this feature request as well: https://feedback.secondlife.com/ldpw/p/compliant-senra-skins-for-child-avatars