No it is simply not "heavily in favor of the nazis".
All sides made prototype units that saw no action and units that did see action (even if produced in limited numbers.)
There is no "favor" here.
The question here is weather such prototype units should be included in the game or not.
I am not sure which question is biased but I find the fact that you are talking about nazis and losing the war interesting.
COH franchise is basically a game ,now if you are suggesting that because it is based in WWII that the "evil nazis" should lose every game, I have to point out that people would simply not play such a game.
I don't think "evil Nazis" should lose every game, I do think that it's macabre in general to reduce this disgusting conflict to a game but that's a completely different issue altogether.
I know that all sides produced prototypes that never saw action - you're not saying anything new. You're not actually responding to my point, you're reiterating your argument and accusing me of bias, something you loathe other people doing.
The "question" I'm referring to is "is this unit 'authentic'?" when referring to things that should be included in the game, particularly when it comes to things which actually saw combat. The Sturmtiger is a great example of my point - it's a purpose-built machine for a very specific battlefield problem. The British made tons of those types of things, but the reason why the Sturmtiger was deployed on the battlefield, outside of its intended purpose, and why combat-ready units like the Meteor were deliberately kept out of combat, or why things like the Black Prince or Tortoise weren't produced and deployed was that the British weren't losing the war and didn't need them. The question of combat use is therefore biased in favour of German tech for the reasons I've stated. Hopefully that's clear enough for you.
Compounding it is the mystique surrounding the Wehrmacht and their supposed wunderwaffen, something that the Company of Heroes series has gladly fed for sales and what the historical community has long debunked. Again, though, that's a completely different issue, albeit one which has effects in this arena.