This Larry Bird fellow is incredibly dumb if he thinks there's no correlation between free throw shooting and jump shooting.
I'm assuming there is some facetiousness in that statement.
I believe Bird's point was that a set, uncontested shot - that is, one that requires no lateral movement or vertical elevation - is entirely different from a jump shot. Free throws require no athleticism or pure basketball form while the same can't be said for a jump shot.
Your assertion that free throws and jump shots are strongly linked doesn't hold water. Go examine the effective field goal % rankings for the NBA. If you look at the top 10 or 15 guards listed, you'll see that their free throw percentages range from 93% to 73%. If there was such a strong correlation between the two skills, it could be reasonably expected that each of these players would have free throw percentages in the 85%+ range.
All of this misses the point Bird was trying to make that the art of the free throw is a practiced skill which requires repetition and form distinctly different from a jump shot.