If people say that Malal isn't happening, Malal makes it so that Malal isn't happening. Or maybe he does make it so that Malal is happening. I have a headache now.

I voted to keep the nids, but the necrons would be welcome as well. A rebel faction, I am sure could be plugged in somewhere and would be nice. The rest of the races, or factions on you list should be playable. Imo.

Or maybe Tzeentch says Malal isn't happening, because he's a Tzeentchian concept! Plot Twist!

All things considered, I don't think Tzeentch actually could manipulate Malal. Neither could the deceiver, or even Eldrad "The Big D" Ulthran

All things considered, his actions only serve Tzeentch, as do the other gods'. Not saying that he would manipulate him, but rather saying that his actions empower Tzeentch.

On top of that, Malal isn't canon anymore as he's not licensed. Retconned in its finest form