The more public-facing a person you are, the harder it is to sue for libel. Suing for libel as a presidential candidate is a catastrophically stupid decision. Not only are you subject to discovery (in this case, Kamala would have to submit her entire wardrobe to the public record to prove she doesn't own a red Stalinist-chik pantsuit), and she would lose the lawsuit anyway because presidential candidates are about as "public figure" as you can get.

It would be the worst possible fight to pick right now. Could you imagine the field-day the right would have if her entire wardrobe were to be made public?