If the Hyper V host wants to continue using the physical NIC after the physical NIC bind to an external virtual switch, we should select the option "Allow management operating system to share this network adapter".
According to your description, other networks seem to be designed for Hyper V host use, so if we use these NICs to create external virtual switch, we should select option "ManagementOS", if not, the Hyper V host can't use the NICs for ISCSI network or cluster network.
Below is an article about the detailed explanation of "Allow management operating system to share this network adapter", for your reference:
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