I would of said everything that skitzo has already said. Thanks skitzo, you saved me a couple of minutes. Btw, nice example to skitzo.
Not really. Think of it more as a city with walls. You're allowed to enter the city with a password (global login system) provided you don't do certain things that are against the rules (cheat, modify, whatever). By entering the city, you get all the benefits that come with it (public servers, login system, etc). If you're caught, you're exiled for X amount of days.
In order to meet with this person, you must leave the city walls so you're out of the city's laws and rules. Anything goes out there in the wildlands.
Basically, a private server is like a LAN server. Homings ban is implemented through the Global login system meaning he's banned from using that system and any server attached to it. Again, since he wasn't connected to it, I'd say he's fine.
Now if it was against the rules for anybody to play on a server that isn't connected to the system, then he'd be "evading". But it's not, so he's fine.