It's not just for people doing interesting things. It just helps people answer questions about stuff. The stuff can be interesting or boring or dangerous or silly. The last question I tested the ACH tool on was "Did William Shakespeare really author all of the works he was credited for?" - You can use this stuff to research whatever you want. That's the point of it - it's no one's business what you are interested in getting to the bottom of.
I can say, from a business perspective, I've needed to use similar methodologies, though far from needing air-gap requirements and relying heavily on web search, to evaluate potentially fraudulent transactions and relationships between parties.
What are the competing hypotheses, other than fraud, when a person makes a massive luxury purchase, but with red-flag-adjacent inconsistencies in other information provided? If we need to identify whether there's a weird or competitive ownership relationship behind a potential opportunity, how do we determine if an initial hypothesis about relationships is correct?
If ArkhamMirror has an online mode with web search as a tool call, I'd be curious to try it out to automate some of these ACH-adjacent workflows.