I think you are going too far with this "DO is an alien" viewpoint. While I agree with you that the DO is not human, he is obviously intelligent enough to understand human behaviour to a significant extent, even if he does not share that behaviour.

If the DO was truly as incapable of understanding humanity and how humans think as you imply, then he would never have been able to manipulate the forsaken and all the darkfriends into believing into his lies and propaganda.

Think of it this way. Our human minds obviously don't work the way the "minds" of computers do. The "intelligence" of the PC that I am using to write this message is in many ways alien to the way my human brain works. And yet even though I don't share the hardware/software I am still capable of comprehending on a purely intellectual level how my PC works.

I think the relationship between humanity and the DO is similar. His mind is alien, but as a quasi-deity he has more than enough intelligence to analyze and predict human behaviour. Enough to analyze and deceive them effectively. Enough to manipulate the more selfish and greedy into becoming his obedient tools. And most certainly enough to understand how Rand would be expected to act in the scenario with Semirhage.