They wouldn’t - the contract is between you and the cruise line only. The ticket contract’s forum/choice of law clause would have zero impact. However, unless

They wouldn’t - the contract is between you and the cruise line only. The ticket contract’s forum/choice of law clause would have zero impact. However, unless your stowaway murderer has assets that could be used to satisfy a judgment against them, any half decent attorney would also want to sue the cruise line as well for their culpability in allowing a stowaway on board (and the provision would apply).