Before Vrigdush died, he got in trouble for summoning a doom knight, the funny thing was, it was classified as a Magical beast, not undead, and was true neutral, not evil. IS this a bug?

I don't think you summoned an actual Doom Knight. There's a certain reagent which summons a creature which has the same avatar.

The reagent in question summons Doom Knights, or I'm pretty certain they're named Doom Knights and they are indeed True Neutral, Magical Creatures.

Okay. Only they are in fact Illusions, which can probably explain that.

That makes more sense now I look at the type of reagent it is. With that in mind, I'm would be inclined to believe this isn't a bug!

This is intentional. Why it is intentional is best explored in game.