From what I know, kevlar doesn't absorb water, like it doesn't absorb resin when you glass it, not even the high temperature high vicosity resin. The resin stays around the fibers, wich is noticable when working the material afterwards.
Flushing the boat clean from salt as described is needed, maybe not rightaway, but I would.
I've seen a second and smaller hole with a ventyl mounted under the steering cap. The reason he told me, was, connecting an air presure pomp to the ventyl en removing the front plug.
The presure pomp, electrical inflatable air pump for a SUP, was enough the create an airflow inside and dry out his boat completely.
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JUST LEAVE FOOTPRINTS