Does the Confusion Spell Affect Ghosts that are Possessing a Character?

Let me lay out the scenario: I’m running a D&D 5e session where the party enters a haunted castle and begins snooping around. They encounter four ghosts and one of the PCs gets possessed by a ghost. After a few rounds of combat, the Druid decides to cast Confusion on an area that the possessed PC is in. I know the following things:

  1. Ghost possession rules state that the Ghost cannot be targeted by attacks or spells unless the attack or spell turns undead.

  2. Confusion “targets” an area, not individual creatures (based on my understanding of what “target” means) so the possessing Ghost isn’t targeted but in the area of effect.

  3. Ghosts are not immune to Confusion because although they are immune to being charmed, Confusion does not state in its description that creatures immune to being charmed are immune to the spell.

  4. If the spell were a fireball or lightning bolt or a different AoE spell, the ghost would be unaffected and the spell would simply harm the vessel.

The party argued that this would mean that the ghost can be affected, especially since the ghost is acting as the PC’s mind. Since they were in a tough spot, I decided to allow it this time, but I told them I’d reach a decision about that sort of thing after doing some research.

Here is my question: Would a ghost possessing a PC be affected by a Confusion spell? My instinct is to think that the Confusion spell hits the PC instead of the ghost and since the PC is incapacitated, the spell basically has no effect.