She was accused of many things in bad faith, e.g. not being Black, being a Marxist, being a communist, and more. Spending time and effort to address every single one of these would have been tantamount to allowing her opponent to dictate her campaign.
https://en.wikipedia.org/wiki/Kamala_is_for_they/them
It was and is an important issue to a lot of voters and by ignoring it she let her opponent explain her position for her.