It does sound a bit weird. On the other hand, if he can influence the choices positively, he does have a point. If not him, someone else would take the job. I would have drawn the line somewhere else but I can understand where he is coming from.
And the fact that he resigned means that he has and likely had some moral compass guiding him.
Absolutely! Unfortunately, we are talking about the US. The article even says explicitly:
“Various U.S. presidents considered and approved billions of dollars in arms sales to controversial nations during his tenure — for instance, to Saudi Arabia in its ongoing war in Yemen.”
So it’s not the first time he’s about to make a very questionable choice. Though I guess he knows some details that blur the lines.