It's nothing to do with the Electoral College.
It's to rig the Senate run-off.
Also, the popular vote will ignore the suburban and rural voters.
For the presidency, if people move states, it won't matter where they are. A vote in california would be worth the same as a vote in Kansas. You wouldn't have to worry about people moving states.
Also, the electoral college literally means that votes for a republican president in california or new york don't count. Same for democrat votes in Alabama and Mississippi. It makes no sense
I HIHGLY doubt that tens of thousands of people are going to move residency to georgia for a few months to offset the senate race. Let's not get unreasonable now....