John Anderson was a Republican who ran Independent after losing to Reagan in the primaries.
He only got 6% of the vote, and a majority of his support came from people who wouldn't vote for Carter, but liked a more liberal alternative than Reagan.
He didn't move a single electoral vote from one-side of the ledger to the other.
Reagan got 50.7% of the popular vote in 1980. If all of Anderson’s votes had gone to Carter (highly unlikely), Reagan still would have gotten 50.7% of the popular vote in 1980.
I’m pretty sure 50.7% is a majority.