My experience with saltwater damage is from my family business in an electronics repair shop where we handled board-level repairs for major manufacturers (including Sony & Panasonic.) The consensus always was from us, the manufacturers, and independent insurers that once we confirm a device has had saltwater in it then it is immediately “beyond repair”.
There are a few reasons… as a repairer you simply cannot guarantee that the device will work once it’s had saltwater in it. The way salt affects corrosion means that if a device passes testing in the morning you does not guarantee that it still might in the afternoon. Repairers simply won’t take the risk when the device might be back in their hands the vey next day.
Typically though you can wash it off, the true saltwater damage is rarely visible to the naked eye. Circuits are very fine so any corrosion issues don’t need to be especially large (or even visible to the naked eye) to cause either a broken or short circuit may occur and there’s no way for a repairer to spot it.
When you look at the potential damage that might come from the failure-mode of the lens it is the kind of damage that could take out your replacement body. If you can afford the risk that you have a ticking time-bomb on your hands that means you may have to replace the body (again) and the lens the very next time you use them (or it may be fine for years) then by all means go for it, but personally I’d chalk it up to experience and replace it now.