When Geist of Saint Traft attacks, an attacking 4/4 flying angel token is put into play. The Geist’s ability doesn’t specify what this token is attacking, so the controller gets to choose. It does not have to be attacking the same player or planeswalker that the Geist of Saint Traft is attacking.

For example, if Geist of Saint Traft is attacking a player, the controller can choose to have the angel token attack a planeswalker controlled by the defending player and not just the defending player. This also works in reverse if the Geist was attacking a planeswalker controlled by the defending player. In a multiplayer game, the token can even be attacking another player or that player’s planeswalker.

Effects that require a creature to attack a specific player or planeswalker do not apply when making this choice. This is because effects that require a creature to attack a specific way only apply to creatures that are declared as attacking in the ‘declare attackers’ step. These effects do not apply to creatures that are put into play attacking in that step. If the defending player controls a Gideon Jura that used its first ability in the previous turn, then the Geist of Saint Traft would have to attack Gideon Jura, but the angel token that was put into play by its ability would not.