Except the bomb they used, GBU-43, is an air burst weapon and not really designed for attacking tunnels.
there is this thing called a shockwave. its power is only partially diminished by physical barriers such as .. the eaerth's crust in this example.
if you have a large enough shockwave, you still kill living things by way of over pressure. This was first tested (scientifically that I'm aware of) by the Nazis in WW2 trying to determine how close they needed to get their bombs to kill everything inside a tank.
At 5M a 250KG general purpose HE bomb officially designated the SC250 killed all animals inside the .. i want to say it was a churchill 3 used as the test tank. Now at 5M there was only cosmetic damage done to the tank by way of blast wave and or shrapnel but everything inside was dead.
Officially that was around 175KG of HE since this is a german bomb that HE was typically a mix of PENT/TNT.
The MOAB weighs about 9500KG, lets go with 7500KG of that being actual high explosive filler.
How far from that blast do you need to be, or, how far and how thick a barrier is needed to survive that?
For more, this episode of mythbusters covers the topic well
MythBusters Episode 178: Toilet Bomb
Also this phenomena was widely reported in Vietnam as well. Many Vietcong were found dead but otherwise 'unharmed' in those tunnels they used to dig. Nobody could figure it out and from what I've read the leading theory was/is death do to over pressure by way of Rolling Thunder.
'Bunker Busters' aren't really designed for this either. Meaning, if you don't have re-enforced concrete to bust through you'll likely just bust straight through and past your intended target. If that is a nuclear bunker buster that could still be fun as you can more or less liquefy the ground and cause extreme damage ... but we wouldn't use that type of device on these clowns.
anyway ... MOAB was still over kill for this. I think Trump just wanted to drop the biggest phallic looking object on these bitches he could find - and MOAB was it.
