la fitness Public Humiliation and canceled my account on my first time there poway California

There are 3 sides to every story, your side, their side, and somehwere in the middle the truth.  You are giving only one side of the story and of course are going to slant it to your advantage.  You apperantly know(or should know) how to "handle yourself" in these type of situations.  Yet you state that this guy apparently just starts off yelling in an "threatning" body stance.  

Then you seem to get a bit heated, and probably more than you indicate here. 

Then amazingly at the top of your hat all of the sudden come up with a "similar" situation that you seem to know all about.  Which is interesting, as it then becomes a mystery why if you knew you would have a possibility of this happening why would you go to a gym that has this history?  Did you want to cause trouble?

I could call the local station on him for CA PC 422 criminal threats which is a FELONY

PC 422 in part states....

422.  (a) Any person who willfully threatens to commit a crime which
will result in death or great bodily injury to another person, with
the specific intent that the statement, made verbally, in writing, or
by means of an electronic communication device, is to be taken as a
threat, even if there is no intent of actually carrying it out,
which, on its face and under the circumstances in which it is made,
is so unequivocal, unconditional, immediate, and specific as to
convey to the person threatened, a gravity of purpose and an
immediate prospect of execution of the threat, and thereby causes
that person reasonably to be in sustained fear for his or her own
safety or for his or her immediate family's safety, shall be punished
by imprisonment in the county jail not to exceed one year, or by
imprisonment in the state prison

---------------------------------

I underlined a key part that perhaps you should have paid attention to when you were going through your instruction to become a VOLUNTEER Sheriff Deputy.

First the fear of harm has to be "reasonable" and "substained".  Since you are an admitted brown belt and a volunteer deputy, one could figure that you could handle yourself in that situation.  Second it has to be a substained fear, and something said in the heat of the moment you really are going to have a hard time proving either of those parts.

Next, this provision can actually be a FELONY or MISDEMEANOR

Now, I will say that since he basically backed down, that doesn't mean you were right...you just bluffed him and actually good use of your Brown Belt eduation.