The Phantom has darkvision 60ft. It does not specifically say WHEN it has it. The Phanton and the Spiritualist maintain a link as a free action. While in the shared consciousness, would it be feasible that the spiritualist would also have darkvision too from the Phantom?
I have to say the idea that it has darkvision when it doesn't have eyes (i.e. while in the shared consciousness) seems pretty iffy to me. Also, the 1st-level link ability doesn't provide shared senses. The 2nd-level bonded senses ability does, but it only functions with a manifested phantom. So... no, it doesn't seem plausible.