PlanetsCentral

Edit: But is money handled differently than clans or supplies? Because these can be unloaded on unowned planets.

(I didn't notice the Edit earlier, sorry)

No, money is not handled differently.

Maybe it helps to understand how the command works internally. It's a two-step process:

First, if you do "unload 123 c20", PHost does the same thing as if you use the regular Unload function: move 20 clans into the Unload transporter. Actually, if you had already moved 10 clans there, the "unload" command will add to that, so there'll be 30 total. The new thing about the "unload" command is only that it can also move cargo and ammo into the Unload transporter.

Second, during the DumpCargo hosting stage, the "unload" transported is operated normally. Here's where rules like "unloading clans to a hostile planet -> ground combat" kick in. It's also that some stages happen before that, i.e. Privateers can rob your unload normally, like supplies or tritanium. At that place, money will be unloaded normally, and added to the planet's bank, even if the planet is unowned or hostile. Ammo can of course only be unloaded if the planet has a starbase that can hold it.

--Stefan