His "accent" is, I think, due to his hearing loss. He speaks like many people I've met with who grew up with poor hearing. I can't speak with authority on that.
I don't care how this sounds, but frankly, Lou's speech impediment ended up enhanced his already excellent performance in the role.
His presence and demeanor already sold the idea that he was the space-equivalent to a ninteenth-century Southern slave trader; sophisticated and indulgent in conversation and feasting, yet brutal, and callously intelligent when it came to his business.
Credit also goes to the on-set direction, as Lou ends up sounding as someone who didn't grow up speaking our language
, yet who's words reveal a stereotype we understand very well. Alien, and not so alien.
is acting, and that's something that not many people without speech or hearing problems can pull off (which I can attest from the theatrical experience I have.)
Good casting and acting all around. Also, bald Hulk is good Hulk.
Having said that, I have to echo Maurice's
critique of the VO on Kirk in the hallway. I actually criticized Exeter for doing this during one of Garrovick's scenes, but here it's both narratively unnecessary and stylistically baffling (TOS never did that, and I can't remember any other shows at the time doing that either.)
Plus, the voice effects added to Lou (which I understand the need for just in terms of normalizing audio) actually made it difficult to understand him in spots unless the camera focused on him (which is okay, since he's excellent at facial expressions). That's a difficult thing to judge objectively, but it's something I noticed.