My new seals have turned up so I can sand off the rusty poles, dust down the magnets, and get it back together.
I was thinking to use some sort of rubber seal for the cover plates, instead of sealant, but then I remembered they are structural connections, it holds the wheel to the bike! So I will get some sealant. Any recommendations? .. maybe bathroom sealant will do?

There is no oil nor heat, just water and humidity, so, why not?
I have thought a lot about how to prevent further rust. I have come to the conclusion that I will simply wipe a very small amount of dexron (motor atf) fluid over the poles and magnets, spread it around to a very thin film.
The reason I have for doing this is because there is very little else that can do the job, and although it might slowly flow to the bottom, this is precisely where the humidity goes and that is where it has rusted.
So, if it is 'oil' it'll go to the same place the water goes to as it condenses inside. As long as it is not much, it will not bung up the air gap, and if it does, then it will only do what it is meant to do and make an oil film between the parts.
I mean, just the thinnest layer I can put on it.
ATF is the oil with the highest material compatibility.
I would welcome your thoughts.