If you really want to find the appropriate answer, I'd ask your local county EMSA. CA good samaritan law falls under Health and Safety Code. It is often revised due to case law.
On one hand you can plead ignorance since you are a soldier that's not trained as a civilian emt or medic. You don't know what is in or out of your scope of practice. On the other hand if you are sued and it goes to discovery that it was even mentioned within your training to not perform invasive procedures on civilians, you'd have a tough time.
With the recent flood of CLS and TCCC training being offered to civilians and PD tac teams, I've seen this question pop up often. These classes often teach straight from the ft Sam Houston manuals with no regard to civilian EMS regs or liabilities. it's even more difficult when the audience has zero military experience or an understanding of where this type of medicine takes place (in austere environments often while under fire).