Wow, labeling anything short of absolute purity as sophistry is, well, sophistry. There is an identifiable and quantifiable difference between wholly owning an entity vs. holding a non-controlling minority stake, particularly in publicly traded companies where anybody can buy shares.
By your logic, if the Saudi fund purchased a large holding in an S&P 500 index fund purety would obligate that we no longer patronize any S&P 500 company. Likewise, since you've previously mentioned petroleum, because it's literally impossible to know where the barrel of oil that became your gasoline originated, I guess purity obligates us to no longer consume gasoline. Those are insane expectations.
It is perfectly reasonable to avoid patronizing Saudi holdings where it is practicable, particularly when they are the clearly identifiable sole or majority interest owners, while recognizing that it would be impossible to avoid every last entity in which they have any level of stake or interest.
Finally, I'd also add that my five figure cruise purchase warrants a higher level of scrutiny and decision-making than my choice of filling my gas tank or which airplane I may fly on. We don't live in a binary world where every decision is clearly black and white.
Sorry to be long-winded about this, but those of us who feel the Saudis taking full or majority ownership of Seabourn would be a deal breaker prefer not to have our integrity impugned.