Bananabixfloof
They did consider including sex. There's a summary of the groups consulted with and the discussions in the Equality Impact Assessment section. Here's a small excerpt, which does at least show that these issues were raised and how they reached the bill as it currently reads. (I recommend reading the full link, this is just a small snippet):
'...A number of options were presented in the consultation as we were already aware of mixed views in this area. Four options were presented:
develop a statutory aggravation for gender hostility;
develop a standalone offence for misogynistic harassment;
take a non-legislative approach and build on Equally Safe to tackle misogyny; or
all of the identified options.
...some stakeholders (particularly Engender, Rape Crisis Scotland, Scottish Women’s Aid and Zero Tolerance) did not want a statutory aggravation on gender to be included in hate crime legislation and have called for the development of a standalone offence for misogyny to tackle the unique features of violence and harassment against women. They are not convinced that the hate crime framework provides an appropriate model for dealing with gender based violence. Individuals generally expressed opposition to, or mixed views on all four options.
Issues raised by respondents across all four questions related to whether any legislative response to tackle hate crimes against women should provide protection to women only, or to both women and men. There was not consensus on this issue, although organisations with expertise in women’s issues believed that the focus should be on women only. Some respondents also said that the protected characteristic specified in the Equality Act 2010 was ‘sex’, not ‘gender’ and that this should be reflected in hate crime laws.
... It remained clear that there were mixed views amongst stakeholders in regards to whether a statutory aggravation should be introduced or not in hate crime legislation in relation to gender. However there was broad support for the establishment of a Working Group to review how criminal law deals more broadly with misogyny. '
www.gov.scot/publications/hate-crime-public-order-scotland-bill-equality-impact-assessment/pages/3/