The "stand your ground" concept has to do with whether a person w must retreat. if he can do so safely, before using deadly force to defend himself against imminent danger of death or serious harm. No connection with strongarm robbery that I can see.
First, we can quibble whether a strong-arm robbery refers to a threat to use force in the form of a beating or whether a strong-arm robbery is the application of force without a threat (someone tries to grab what you have and you struggle with him). I see the two as different. The robber who explicitly issues a threat, IMO, presents a greater risk. In some neighborhoods, people make sure not to leave home without at least a few dollars on their person because they know that if they get robbed and don't have any money on them, the robber can get infuriated and beat them severely. But let's not quibble.
Here is the connection with strong-arm robbery that I see. The website states that the robber gives "an ultimatum like 'give me your money or I’ll hurt you'." This is an explicit threat. Since you are not legally required to agree to turn over your money, it's not a conditional threat. Personally, I would turn over the money, but a victim would be well within his rights not to. (Of course, so would I but I wouldn't be interested in asserting my rights at that moment.)
Therefore, if the victim is not going to turn over his money to a robber, he would, IMO, have a reasonable ground for fear of imminent serious harm. Now maybe the victim knows the robber and thinks the robber is some kind of punk who talks big but won't use any force. Or maybe the robber is 6 years old. Fair enough. In those cases, the victim can't use force because he doesn't truly believe he is in danger. But the typical strong-arm robber does present an imminent threat of serious harm. That's why people turn over their money.
And self-defense can apply to resisting a robbery in and of itself.
Here are the instructions in CA for self defense in the case of justifiable homicide:
1. The defendant reasonably believed that (he/she/ [or] someone else/ [or] <insert name or description of third party>) was in imminent danger of being killed or suffering great bodily injury [or was in imminent danger of being (raped/maimed/robbed/ <insert other forcible and atrocious crime>)];
2. The defendant reasonably believed that the immediate use of deadly force was necessary to defend against that danger;
AND
3. The defendant used no more force than was reasonably necessary to defend against that danger.
In addition to "imminent danger of being killed or suffering great bodily injury" there is the alternative choice (depending on the case) of being "in imminent danger of being ... robbed."
Here are some other instructions that might apply:
A defendant is not required to retreat. He or she is entitled to stand his or her ground and defend himself or herself and, if reasonably necessary, to pursue an assailant until the danger of (death/great bodily injury/ <insert forcible and atrocious crime>) has passed. This is so even if safety could have been achieved by retreating.
Great bodily injury means significant or substantial physical injury. It is an injury that is greater than minor or moderate harm.
"Stand your ground" in CA therefore not only means not retreating but also being able to "defend himself or herself" while doing so.
I read these jury instructions to mean that, assuming one one may lawfully resist a strong-arm robbery by using force.
Is it possible that a victim of a robbery who shoots and kills an unarmed thug who is in fact attempting to rob him could be prosecuted for using excessive force? Yes, but I see that as unlikely. A strong-arm robbery by its nature will take place with the victim and robber within striking distance of each other. Simply drawing a gun or knife in self-defense risks immediate (if perhaps ultimately foolish) attack by the robber.
To avoid igniting a debate on the issue of pursuit, everyone please note that the right to "pursue an assailant" ceases in this circumstance once the danger has passed.