In my case, the two cars have opposite reasons for sitting out the corrosion onslaught.

In the PV's case - it's already had too much exposure to salt. It's falling apart under there. Floorboards and sills all replaced (fairly poorly) by the previous owner. Bits of subframing missing. A decent amount of MIG welding and patching has gone on to keep important bits attached. It's as solid as it needs to be to be safe to drive, by a small margin. But it really can't handle much more rust and corrosion at all, so any salty road use would hasten it's demise considerably. And I'd miss the little beast.

And in the case of the 245, it's just too much of a cream puff. There isn't the slightest bit of rust on the body anywhere, and I'd just like to keep it that way, instead of fighting it back later on. I've sunk a lot of work and money into modifying it, I want it to stay looking good and solid for a very long time to come.

And when it snows - the 4Runner is simply a lot better equipped to handle it. And they made 394 million 4Runners, if it gets too rusty, easy to find another one. Replacing the 245 (16V turbo Classic edition) would be much more difficult. After all, there's not just salt to worry about in winter driving, but other yahoos driving poorly.
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'63 PV544 rat rod, '93 Classic #1141 245 (now w/16V turbo)