I wouldn't call that a good sign of leadership. That's more an act of shutting everyone else off from access to technology.
Instead, a good leader will help lift others. Take Microsoft Research. For a long time, they were a leader in scientific publications in CS, with many awards. Compare that to Apple, and imho any sign of "leadership" is completely non-existent in comparison.
Apple has done far more than any tech company to take ownership of their supply chain.