What indeed was the situation with Jack Ruby? If he was not a knowing conspirator, was his killing of Lee Harvey Oswald manipulated by mind control?

This indeed is the case, and you have solved the last piece of the puzzle with this insight. He was an odd character and did have mob connections and was a police buff, so to speak, who wanted to access both worlds, and befriended many police officers as this was advantageous in many respects, to have wider context to exert influence and to obtain favors and engage in various forms of kickbacks and bribery to help some of his illegal activities not receive police attention. So he was comfortable in that environment and he was pressed into service as an assassin through mind control manipulation. This was quite easy to do, as Ruby often carried a revolver and he was well known to have a severe temper and was not able to control it once aroused. So it was a simple matter to create anger within him and give him the impulsed idea to lash out at Oswald with the combined thought that he would be a hero in carrying out this act. This was distorted thinking but is no different than the case with the many, many, acts of terrorism, almost all of which are engineered by spirit meddler influence and extraterrestrial mind control manipulation. And the most common scenario is a combined message of urgency to right a wrong of personal interest to the potential terrorist, and then to dangle a reward that is sizable and irresistible. So this is a perfect match in all respects, an individual with a history and track record of violent behavior that could be triggered and quickly escalate out of control, and use of firearms as well. And he represented a perfect tool to use as a human weapon to tie up the loose end left by Oswald still being alive. The original expectation was that he would be killed by the police during his arrest or before being arrested because of the death of the police officer creating such passions and this came very close to happening to Oswald. So there simply needed to be an additional means to eliminate him. There could have been many such events engineered as there are always many people with a violent nature who have an ax to grind, so to speak, who could be entrained and manipulated to carry out an act of revenge. As it happened, Ruby was the closest at hand, through his past history and his fascination with police work and ready access to the jail, which served nicely to make him close to the event in a special way not felt by those simply watching things on TV. And this primed him emotionally to have the extreme degree of manipulation so very effective in arousing his passions.