No. No. No. The shot is from the 6th floor, not the fifth. It is at a target that is going downhill and to the left slightly. A pretty flat shot. If it came from the grassy knoll, it would have been at a moving target going from left to right. A difficult shot. Besides, Zapruder’s film would have caught that shooter.
The grassy knoll is all of 30 yards away. Super easy shot.
The window is about 18m up. The distance to the x is approximately 60m. This is a 16 degree declination on a moving target. The target is moving left to right at approximately 30 degrees away from the depository at 25mph. That is not an easy shot. The grassy knoll is approximately 40m from the pint of impact with the target at the same elevation and coming almost straight in.