Proportionality” is not a factor in the use of defensive force.Simply not correct:

I suggest you read your link, because it does not reflect your argument. Proportionality does not mean "if she uses 30 newtons of force against him, he is not justified in using 32 newtons against her." It does not mean "if she throws two punches, he is prohibited from throwing three". It does not mean "if she uses a knife, he is prohibited from drawing a gun". It does not mean "she drew only a .32ACP, so he is not justified in using a 9x19 to stop her".

Your link uses substantially the same words I said:

The core idea is that your defensive actions should not exceed what is necessary to prevent harm.

Necessary to prevent harm. Defensive force can significantly exceed the attacking force if the defensive force is necessary to prevent the harm from the attacker.

Courts and legal systems apply a "reasonableness" test. Would a reasonable person in the same situation feel compelled to use the same level of force?

Again, you have to demonstrate that it was unreasonable to think she was continuing her attack at the time of the kick, and/or that the kick was excessive, and intended to cause greater harm than simply putting her back on the ground.

The examples from your link further demonstrate my point:

If someone attempts to slap you, blocking the attack or pushing them away might be reasonable; pulling a knife would not be.

He shoved her away as she slapped him. When she got up (and he reasonably believed she was continuing to attack), he kicked her back on the ground. Absent some statement of intent to cause excessive harm, these are greasonable use of force.

If a home intruder brandishes a weapon or threatens deadly harm, using proportional deadly force to defend yourself may be justified.

In a physical altercation, a beer bottle is a deadly weapon. He used a harder shove to prevent her from causing harm with that weapon.

If an aggressor backs down or flees, continuing to use force may no longer be proportional—and can become criminal.

He stopped using force when she stayed on the ground. He was justified in keeping her on the ground, preventing her from attacking again. he was not justified in using force while she stayed on the ground.

On the flip side. He backed away from her after the kick, and after the final shove. Even if she had been justified in using force before that (she wasn't) that retreat eliminated any justification she would have had in using force against him. Yet, she grabbed a beer bottle and escalated to a threat of deadly force. According to your link, she is the one who violated the "proportionality" standard.

Can you provide a screen shot of the moment where her hand actually connects with his face in the form of a strike?

You are telling me you can't see her right arm move in a leftward motion, over his left arm, toward his face? I do not believe your claim on this point is genuine.

I don't know why you continue to press this issue. Even if you can't see the actual strike, you've already indicated her actions can be reasonably construed as an "angry push". Strike, push, shove, lunge, : these are distinctions without a meaningful difference. Even if she doesn't actually make contact with his face, anyone in his shoes would reasonably believed she was trying to strike him. That's all he needs to justify the push, and the subsequent kick.