Ground stations are required to correct the sats (or synchronize). It probably won't affect civilians. But military/high precision services using GPS will definitely get affected...
If it was "Niyyat" that is what mattered as you said, prayer could have waited till he got to some proper place. But no, he had to do it in open and on a footpath just because it was time for prayer?
Somebody should stand in front of him. I did it couple of times when lot of people were doing namaz in public place, felt like they were all worshipping me. Felt awesome for some time.....