I'm not an aerospace engineer either, just a random guy. Thank you for showing the mechanism of loitering capability.
I'm just not really understanding the value of doing so in a very high threat environment. Is the PLAAF assuming it will have air dominance and fighters scrambled in response to a VHF radar detection or things blowing up will not be an issue? Otherwise if there's an intercept going up, wouldn't you want your strike assets to flee?
Good question and all.
So the US in the early 2000s started defining what the next gen bomber gonna be like and did alot of studies to choose the right requirements. Initially, the logical choice would be stealthy extended supercuising bomber that spends the least amount of time in contested airspace to complete its mission. What they found eventually was that an ultra stealthy stand-in bomber (staying extended time within contested airspace) that can immediately respond to pop up threats is more effective than a high speed bomber that has to be launched and rushed toward the target that may have already completed its mission and disappeared.
This means that this bomber has to be ultra stealthy against wide spectrum of detections (low frequency radars and infrared sensors) and long loitering time. This means subsonic long leading edge flying wing.
You may also ask why the ability to respond immediately to pop up threat is important - because that's where warfare is heading. The russian ukrainian war only reinforces this. From SAM systems to artillery, the driving requirements are mobility and less stationary times in order to hide from enemy's counterstrikes.
So you may ask how feasible is it for a bomber to lingering around after it has opened its bomb bay or launched a missile and immediately get picked up from dozens of advanced MLD's in the air. Well, the answer is not that if it is feasible but that it has no choice but to be feasible. That's the challenge to overcome for engineers in both the B-21 and the H-20 programs because to be effective, you need to fullfill this particular capability.