Why did the French parliament declare the throne vacant after Charles X abdicated?

Following the July Revolution of 1830, Charles X abdicated on August 2, stipulating that the throne should pass to his grandson, the duc de Bordeaux (the "miracle child").123

However, the French parliament rejected this condition. When the parliament convened on August 7, it declared the throne vacant, effectively bypassing the succession of Charles X's grandson. This decision was part of a broader effort by constitutional monarchists to establish a new regime that would avoid the risks of republicanism while securing a stable constitutional monarchy under Louis-Philippe. By declaring the throne vacant, the parliament asserted its authority to determine the nation's leadership, leading to the proclamation of Louis-Philippe as "king of the French" on August 9, 1830.134