In Transformers: War for Cybertron - Siege, Megatron wanted to 'eliminate' the Autobots by using the AllSpark. Therefore, Optimus Prime devised a plan to obtain the AllSpark before Megatron did and take it off Cybertron with the Ark through the space bridge.
At the end, though, in a battle with Megatron, Optimus Prime was forced to throw the AllSpark into the space bridge hole (thus moving the AllSpark off Cybertron without use of the Ark).
Why did Optimus Prime still take the Ark through the space bridge afterwards instead of destroying the space bridge? Wasn't the mission already completed by moving the AllSpark away from Cybertron, and thus keeping it away from Megatron?
What is the effect of moving the AllSpark off Cybertron for life on Cybertron (besides stopping the plan of Megatron)? It seemed to have been suggested that the AllSpark was needed in order for life to exist on Cybertron?