Well sure it's fun to speculate.
Let's look at it this way.
We're planning the hit. We need a 'mop up' guy in case something goes wrong.
They approach Greer and say, 'we want you to be the backup guy. Here's a dart gun. If we miss, keep an eye on JFK and shoot him with this.'
Wouldn't he be a fool to agree to this?
So what, he's got to drive the car, stop it and enable the hit and then if they miss, he has to blatantly turn and shoot him and then dispose of the
weapon and hope nobody noticed?
That's just ridiculous on the face of it.
So you've seen what you thought was an object in his left hand. You've seen the CIA weapon and you put two and two together.
But in promoting this theory you have to throw out common sense.
The SS is high profile. If they have any involvement it has to be subtle and enabling, rather than blatant or overt.
Having a weapon concealed somewhere in the car body is the way to go -IF- you're going to insist on a man there to mop up. The SS have control of the
vehicle and can remove all traces. You really can predict where he's going to sit.
Though it's fun to make theories, what do you really have? A dark shape in his left hand near the steering wheel? Most people can't even shoot that
well with the non-dominant hand, let alone turn and reach across their body and at the same time drive the open top car.
I'm telling you, the guy might have been an enabler, but he's NOT going to agree to pull triple duty like that.
There's nowhere to dispose of the weapon. There's a chance he could miss or the weapon misfire, and the location not isolated enough.
Now you have Livingstone -and- Gov Connelly in on it?
I think you're just too far afield on too many points for this theory to have any validity.