You really don''t want to use the shrouds as part of the grounding system.
Stainless conducts electricity, but not as well as an aluminum mast. In the event of a strike you likely suffer shroud or fitting damage due to internal heating.
On a normal protection system, the mast forms the primary grounding point to either the keel or a submerged plate. The shrouds are only tied in to lessen side flashes and crew injury.