Question: Does affirming the Throne and Footstool imply that Allah needs their support?
Answer: Certainly not. The Throne and Footstool are created realities. Their Creator has no need of created support or location, and His independence remains absolute.
وَالْعَرْشُ وَالْكُرْسِيُّ حَقٌّ
The Throne and Footstool are real.
Follow-up: How should their affirmation be understood?
Clarification: Affirm the created unseen realities while refraining from assigning creaturely modalities to Allah. His knowledge and encompassing power are affirmed in a manner befitting Him.