MindArk can't forbid customer IRL interaction. That would put them in the hot seat in both US and EU courts.
That said, you're facing the same problem as any remote interaction with money involved. You basically need an a third-party escrow, or meet the person IRL.
This company (netteller, was it?) wants you to trust them enough to forego escrow. Chances are this company is more trustworthy than random Joe in EU (which, let's be honest, attracts scammers like a pile of manure attracts flies).