No, neither the BE or the American have such a limitation.
I'm not sure what would cause you to doubt the validity because it is BE coaches voting. Are you also doubting the validiy of Paige being named Conference player of the year?
All-BIG EAST First Team
Paige Bueckers, UConn, Fr., G*
Christyn Williams, UConn, Jr., G*
Lexi Held, DePaul, Jr., G
Sonya Morris, DePaul, Jr., G*
Selena Lott, Marquette, Sr., G*
Leilani Correa, St. John’s, So., G
Desiree Elmore, Seton Hall, Sr., G/F
Andra Espinoza-Hunter, Seton Hall, Grad., G
Lauren Park-Lane, Seton Hall, So., G
Madison Siegrist, Villanova, So., F*