How does malvolio help viola and Sebastian reunite?

Malvolio inadvertently aids Viola and Sebastian's reunion by creating a series of misunderstandings that lead to mistaken identities. His misguided attempts to woo Olivia, believing she loves him due to the forged letter, draw attention away from Viola's true identity. Additionally, his imprisonment allows for the comedic unfolding of events that ultimately brings Sebastian and Viola together, as the chaos surrounding Malvolio's antics creates opportunities for their paths to cross. Thus, his actions, though self-serving, contribute to the eventual resolution of the play's central conflict.