Whether it is plausible, possible, could have happened or is in fact BS there is one point that stands:
The writing is crap. It's written from the perspective of an immature person with more of an interest in pseudo heroic bravado than any real intention to convey authenticity. It is commonplace. Many a soldier writes home to family and buds with a story to intrigue the uninitiate. We all want to see cool stuff and do great things (and some do) but the writing style of this piece carries with it the realism of a, forum post (was going to say "dime store novel" but that's not fair to the medium). Now, I'm not just basing everything on whether the soldier can put two words together in a compelling way; there are points that beg attention here.
1. "pitch black, crystal clear night". Hmmm, you'd think a trained killer could at least describe the environment in concise, relevant terms.
2. A B-1 Pilot offers to perform a "show of force" even though he asserts there is no one in the area. BTW, the Pilot's authority to perform the maneuver comes from centcom so there would likely need to be a really compelling reason for them to provide approval. "A few shots fired, but no big deal" isn't likely to cut that sandwich.
3. I don't know what anyone else's version of "God just hit you in the head with a hammer" is but breaking the sound barrier at 1000' above your head isn't going to amount to squat. Sure, you're going to hear it - but you're not going to need earplugs much less feel as though any kind of show of force has taken place. Been there done that: Stationed aboard the USS Missouri BB-63 I've seen a few sound barrier flyby's first hand. Impressive to say the least, "Hammer of God" type of impressive... ahhh no. And we're talking less than 200 yards out, so this B-1 pilot would have to have been right over their heads for them to feel it as described. I would hope to think though, a trained killer could tell the difference between 'just over your head' and one thousand feet (1000').
4. B-1, flying supersonic "stands it straight up" and blah blah blah... I'll let the physics and Jane's aficianado's address that one.
5. Soldier's referring to themselves as trained killers... I have quite a few friends and family in theater, two of which are Airborne. They just plain don't talk like that or refer to themselves that way much less write home of their grandiose exploits in such a fashion. Perhaps my family/friends are just a different sort of person. It strikes me as being odd is all.
6. Supposedly the pilot asks two questions which are replied to with "Stupid question. Of course we tell him yes." and "Very stupid question". There are just too many issues with that. One, let's say the questions were asked. My money is on the likelyhood that the Pilot is just a wee bit more intellectually capable than the ground troops (not a slam, just an IQ probability being that all we know of these particular soldiers is that they're "trained killers) and likely have a very good reason for asking questions to specify a manner or type of maneuver. To refer to the pilot as having asked a very stupid question in light of a very obvious answer - well, I'd say that particular trooper really isn't trained well at anything, much less killing.
I've spent hundreds of hours in the Combat Information Center (CIC) of the battleships and destroyer I've served on (Gulf War I inclusive) and communication is clear and concise for a reason. Strategic calls, no matter how plain Jane and "Obvious" to all involved are double checked and verified before executing. There is nothing "Priceless" about assuming the intentions of a joint military maneuver.
I'm not saying a "show of force" didn't happen or doesn't happen or that it isn't worth or exciting to write home about. I'm saying that it didn't happen the way the post portrays, if in this story it happened at all.
BTW, for the google inclined there is plenty of test footage of military planes performing sound barrier runs - much of it within 100' of audio/video recording; so one can judge for themselves, even if poor quality whether a "Hammer of God" effect would be experienced anywhere near 1000'. I've been there done that - so I call BS.
Cheers