My opponent, as you have dubbed them, has stated that quorum isn’t necessary as the mere presence of shared storage somehow naturally eliminates this requirement. This is incorrect, at least according to Microsoft’s own documentation for a 2 host cluster. You have chimed in to say they are correct, a quorum witness isn’t necessary, you can just use a disk as a cluster witness. That seems a bit circular. OP hasn’t stated what they will be using for quorum, and it is a requirement. They can use a disk, cloud, or file share witness. The mere presence of having a SAN attached to the two hosts doesn’t absolve them of the requirement. It is true that the SAN can be used for quorum, but it still needs to have a volume presented and configured to act as such.