That is tin foil hat nonsense even by prior low standards, but why would LBJ need a signal? Even if he was involved in the assassination plot, he would see for himself if anything happened. He was in the motorcade. He wouldn't have any action to take in the act other than to become President if it succeeds. If he needed a signal, however, why couldn't it be yellow roses? I will give you some credit though. Some sources suggest LadyBird's flowers were white but they do appear to be yellow in the color photos. The flower on LBJ's suit is white.
why would LBJ need a signal? LBJ didn't need the signal, but the killers wouldn't have fired unless they had assurance from LBJ that he'd cover their backs....So the Red Rings were multipurpose....
A) A reminder to JFK that he had betrayed the killers when he pulled the air cover that the CIA had promised would be there at Red beach at BOP.....The umbrella man with his umbrella, was also a reminder to JFK that he'd pulled the umbrella of air cover at BOP....
B) A signal to LBJ, that the trap was set and the patsy was staying out of sight on the first floor .....
C) LBJ's signal to the killers....Proceed....I'll cover your backs....