It's... well, boring.
No offense, I like the idea of it, I like the fluff behind it. BUT I don't see the purpose of it.
Now, before I continue, let me say that I applaud the effort. As a Thousand Sons 'loyalist', I am one of the first people to suggest that if you're playing Sons, you skip the demons, the dino bots, etc etc.
But when you do this, what are you left with? Almost nothing when it comes to Chaos. That's why (and
will attest to this) I spend most of my time building Thousand Sons as Vanilla marines with fancy hats. Or Grey Knights. Or hell, even Necrons. They all do the job better.
I think the same thing happens with Alpha Legion.
So let's look at what you've done here. You have a standard Force Org Chart. check.
You can't have anything with Marks. Ok. No Cult Troops. No Demon. That removes Heldrakes, Obliterators, Mutilators, Forgefiends, and Maulerfiends, Princes, Defilers...
So what are you left with for your army?
Dark Apostle (by rules, but why would you ever have one in Alpha Legion?)
Warpsmith (I can't remember here).
Tanks (Rhino, Predator, Land Raider).
You get access to Infiltrate, once per game Preferred Enemy, Stubborn, and a fancy Warlord thingie.
Couldn't you just glue some spiky bits to Ravenguard? Paint Ultrasmurfs black, maybe?
It just feels like you've removed SO MUCH of the Chaos Codex, that just like 'loyal' TSons, you're not doing enough to earn your fluff back.