From: The Great White North!
I certainly could have included a B-1, however, there are already so many assets in theatre that there is generally no doubt that a US player will overwhelm North Korean defences, especially with indirect help from Russia.
So the choice was a non-stealthy bomber(s) with a decent bomb load or a stealthy bomber that could deliver the GBU-57 MOP. Considering the target set, I felt that the MOP would probably be required, therefore a B-2. Any more than one bomber would probably be a little overkill, although it might be realistic to have one or two B-2 and perhaps 8-10 B-1 loaded with JASSMs in this situation - 240 JASSMs would mean much of the USAF and SK AF could stay home and take a break.
The other key consideration was stealth. The USMC F-35 Sqn deployed to Japan in early Jan, and I felt that these, combined with a couple ready Raptor Sqns would complement the B-2 quite well, where the B-1(s) would just hang out over Japan and start lobbing death and destruction all over the place. Since the MOP needs to get in close and personal, the strike takes real coordination between very interesting platforms.
So you have a very good point but the choice was made more for game balance and interest.