The reason the Samaritan is used is that it is too large to be loaded onto a normal bomber, even the B52 and is pushed out of the back of the loading doors.
May I suggest you do a web search on the C-131 Samaritan aircraft and compare it to the B-52. I imagine it was just a typo, but the aircraft used was the C-130. AS I said, the C-131 was phased out back in the 70's and had no cargo doors in the back, but the C-130 does.
I have seen the B-52 in action and it would have no problem carrying that bomb, if needed. Trying to connect it to the Samaritan is a real stretch as that aircraft hasn't been in use with the military for many years.
Right now, it is called as much a psychological weapon as anything else and yes, I fully believe it was "tested" when it was to send Saddam a message, a message of not wanting to use it, but that it could be. Also, much information on it is highly classified at this time, so what info is out there may be more speculation than anything else.
But wait, they are also working on another version of 30,000 lbs. In comparison, the OKC bombing was about 2,000 lbs.