It is not true that GPS technology works by using magnetic fields on Earth in order to find a particular location. Instead, what happens is that GPS satellites which orbit our planet transmit various signals at the speed of light in order to convey such information. These satellites send out signals, the receivers on Earth read those signals, then they measure how near or far the signal is, and then pinpoint the exact location. Ultimately, it has nothing to do with magnetic fields.
It is significant because a prominent leader was suggesting that the unequal treatment of African Americans was in direct opposition to the principles of the Declaration of Independence.