I wanna point out how unusual it is for this guy, who was purposely spilling wine on Alastor and laughing,
to willingly follow him all the way out into the bayou.
The subtext in this scene doesn't show a man who was kidnapped and drug out into the woods, it shows a man who was taken by surprise after coming of his own volition but why would he do that when he was openly disrespecting Alastor beforehand?
The man is fully dressed as he is in the wine spilling scene but for some reason Alastor is no longer wearing his vest and his shirt + tie are completely undone right before and during the murder, not after. I'll bring attention to another scene:
You could argue that the blonde guy's shirt being open like that happened because of the stabbing but again, on the other hand, Alastor's shirt looks to be carefully undone, not ripped like it would be in a fight. Now I want to bring attention to two things. First:
Now this is in reference to clothes getting ripped during a fight but the way he frames it here is meant to be a double entendre for people attempting to strip him for the purpose of sexual activity, he's implying that that's happened before. Next:
I think many of us agree Alastor was acting seductive with Vox to get him to do what he wanted him to here and now I want to go back to this:
Why would this guy go with Alastor all the way out to the middle of the bayou? Because he lured him there by seducing him with the promise of sex.
Alastor's human form is clearly meant to be considered attractive and desirable, Rosie even admits that upon his introduction and refers to him as a charmer as well. He's shown us experience in seduction, we see that during his deal with Vox and notably the scene where he was using the flexibility of his legs and provocative mannerisms while provoking him.
And I want to point out how we can visibly see a wedding ring on this guy's finger.
I think what we're meant to take away from the subtext of the backstory is that Alastor was sexually tempting and flirting with his victims. He managed to charm men like the wine-spilling racist by using his "exoticness" as a mixed man, his beauty/sex appeal and his charm to lure them out to where he can murder them easily.
That would also explain why he's partially undressed in these scenes and explain his comment about people not being able to take much of his clothes off (because he attacks them once their guard is down.)