Depends what you mean by freezing up. Pretty much everyone "freezes" for a moment when confronted with an unexpected threat to life. It's an evolutionary threat-assessment thing. How long that lasts is a matter of personality, exposure and training, and yes, women generally fair worse. The freeze response you're referring to is quite different though.

If you've hunted, or legitimately startled someone in a self-defense situation, you'll know that the freezing is accurately named. Think stunned rabbit. Rapid breathing, wide eyes, minimal to no movement, incoherent mumbling or repeated simple sentences.This is not it. She did respond, and her response was to exploit a social network against the threat. A predictable outcome.

That said, it's a shit situation, and one that could have easily required escalation. I'm more concerned about the fact that she closed distance on, and repeatedly put herself between two potential attackers - both of whom where unresponsive to verbal orders and willing to kill a man in front of a cop. Unless this is some rural melodrama and they're her cousins, that's terrible self-preservation right there.