What evidence do you have that suggest this is another player and not a VPN? Or they aren't actually traveling? No idea why you would VPN for PK I guess.
The main question is, why would it matter? Players allow others on their accounts all the time, seasonal things or just simple get on their account to be a troll. Regardless. Not. Much can be done about it. Pretty sure as far as my knowledge goes letting others on your account is your control. But it's just wise to not do so or only let people you trust on it