Crashing starter before fermentation stops

I made a 2 gallon starter for a doppelbock I am brewing soon. The starter has slowed dramatically and I was wondering if it would be okay to cold crash now to give the yeast plenty of time to settle out, or would this cause harm to the yeast?

You can either crash and settle, or pitch at high krausen. What you don't want to do is keep it warm after the yeast have done their job on the starter. That just tires the out.

If you cold crash then the yeast will have a chance to build up their glycogen reserves and if your plans change it allows you the option to keep the starter without consequences.

So to anwer your question, yes cold crash now and you'll be good to go.

I usually always crash my starters, even for ales b/c I don't like adding extra wort to my beer (even tho it doesn't matter for a 1L starter, I'm just anal). With a 2 gallon starter I definitely do not want to pick that into my beer

I wouldn't cold crash before it's finished! The reason for making a starter is to reproduce yeast. Either pitch it at high krausen (the whole thing), or wait until it has finished and then chill. Chilling it during active fermentation will be counterproductive, in my opinion.