Other than it boosting the songs on iTunes, it was kinda smart of Bobby: Many people probably bought one of the songs, maybe both, for a discounted price, and now that they have it, buying #Joanne will be less expensive for them, if they decide to / other songs grow on them.
Not only does it boost the songs, it also helps the album.
Tbh Gaga should be a pioneer once more - discount all her music, permanently. iTunes is on life support anyway, she's not making money from digital sales so she might as well do what she can to sell the most before the platform dies completely.