Depends on which you consider to be the "general" rule, and which the "specific".
You could say "In general, UMD lets you mimic a racial requirement, except for Warforged Components."
You could say "In general, you can't use Warforged Components unless you're a Warforged, but if you can mimic being one with UMD, you can."
I'd be inclined to go with the second interpretation, seeing as how that is
exactly the situation UMD describes itself as being useful in.
Some magic items work only for members of certain races, or work better for members of those races. You can use such an item as if you were a race of your choice.