It seems like you're calling this out as if it's a negative. MS Access is perfect for a situation like that - available, disposable, and easy for semi-technical people to use. When the community talks about "everyone learning to program," this is what it would look like.
They don't have the authority or budget to set up something permanent just to catch a couple dudes, and frankly they probably don't need something permanent. They just got it done quickly and with the tools on-hand.
Indeed; wouldn't we be ... concerned if they'd used a multi-user database?
For 150,000 records, Access for them, perhaps a Perl or whatever script for us, and then you abandon everything but the very small number of specific hits.
This legitimate use is unfortunately the justification for the NSA's Hoovering of telephone metadata, e.g. you can't tell a judge ahead of time the specific numbers you're looking for until you've correlated them against your initial lead.
They don't have the authority or budget to set up something permanent just to catch a couple dudes, and frankly they probably don't need something permanent. They just got it done quickly and with the tools on-hand.