From the survey:
Who are the intersex respondents?
The LGBTIQ Survey III collect the life experiences and views of respondents who identified themselves as ‘intersex’. Intersex persons are born with innate variations of sex characteristics (SC) – such as sexual anatomy, reproductive organs, hormonal structure and/or levels and/or chromosomal patterns – that do not fit the typical definition of female or male. The term ‘intersex’ is an umbrella term for the variations in sex characteristics that occur naturally; it acknowledges that sex is a spectrum and that people with variations in sex characteristics other than male or female exist.
While many intersex persons also identify with other LGBTQ identities, it is important to recognise that intersex is distinct from gender identity and expression (GIE) or sexual orientation (SO). Not all persons with innate variations of sex characteristics identify with the term ‘intersex’.
From The Guardian:
All of them identified as intersex, an umbrella term referring to those with innate variations of sex characteristics and which includes people who identify as trans, non-binary and gender diverse.
The Guardian has misreported this. Or, at very best, it's making deliberately cynical use of ambiguous syntax.