Trying to judge your case is like us trying to be better than the jury on Court TV when we don't get all the facts. It's impossible.
You guys that are arguing principles never heed the advice to "choose your battles"? Is it worth it for "I won't be spending $ 10K on this, although it is costing me money. The lost sleep, stress on my kids, stress on my wife and stress on myself have a cost though and someone is going to have to pay". If this backfires, you face jail time and/or additional big legal fees.
Don't assume a slam/dunk and enjoy the pat on the back from the lawyer. My wife was rear ended, resulting in her getting pushed into the car in front of her. She was ticketed. We fought it with a lawyer and witness and LOST. The judge was having tooth surgery that day and was in pain. You NEVER know the outcome.
Based on the lousy tape and you description here, the persecutor will have a field day with you as follows:
P: Describe the altercation.
Don: "the greeter actually attacked me, you can see him lower his left shoulder as he drove into me, the greeter charges into me and pushes me back".
P: the tape shows the greeter gingery moving toward you, he didn't raise his arms, take a kung fu stance, nor does he appear to throw himself into you.
Don: his chest touched me and he grabbed my arm.
P: So you say that a "bump" and grabbing your arm equals a violent attack requiring a violent reaction?
P: describe how you pushed him.
Don: "I pushed him off with me right hand only"
P: The tape clearly shows your upper body mass moving in the direction of the shove. Which was it, one hand, or a heavy body weight push?
Don "I gave him a pretty good push"
P: First you say one arm only, then a pretty good push, and the tape show your upper body into the shove. Which version is correct?
P Describe your altercation with Tiny.
Don: "the other goon stopped me with what looks like an elbow to the neck area"
P: previously, you stated "In addition, I have no recollection of Tiny touching me or raising his arm at me like that".
Don: It all happened so fast.
P: So, you are saying that you really don't remember what actually happened.
P: Don explain your statements "He was pushing me into the wall".
Don .......
P: the tape shows you NEXT to a corner with open space behind you. Again, you appear confused what really happened.
You get the idea. And, nice as it is that your wife is a nurse, the persecutor has somewhat unlimited resources to hire as many expert witnesses to taint the jury's ideas as he chooses.
Malicious prosecution - ha! The judge has heard that game a million times and could give a hoot.
Not trying to be the devils advocate here. Just trying to show you what three ring circus will develop.
My opinion, this will go beyond the legalities of what the greeter did and will rest on your description of the law:
"No person in the state shall be placed in legal jeopardy of any kind whatsoever for protecting by any REASONABLE means necessary,"
Was your hostility REASONABLE? Why didn't you push Tiny? Did you consider saying "don't touch me, please get a manager"? Was this old man (I assume he matches other greeters - old man with weak back and one foot in the grave) a threat to you? You seem to have sent him sailing with "just a push of a hand". do you have any record of trying to write Walmart about your dislike of receipt checking? Do you have records of talking to WM managers in the past about your dislike of......?
I think you have a tough road against you. A sweet old man with weak back against a guy who is "upfront and doesn't back down". Who cares if the greeter was in the wrong, the jury will conclude that you reacted with UNREASONABLE force for the simple act of not showing a receipt (cue the violins).
Again, info offered as help. I choose not to take sides without all the facts (or fiction). I too, once lived in the fantasy that justice will prevail. Oh sure, officer, you are welcome into my home. Once I tell you the truth, everyone will see that I am right. Ha!
Personally, I would not be discussing this case with the world. EVERYTHING you say/post, REALLY, can be used against you.