Had he used an ethernet connection, that is, a cable, he would not have broadcasted his traffic to the neighbourhood and police would have needed much more of a clue where he lives (not just "this general area") and also a search warrant.

What's particularly remarkable is that not having wifi at all at home, or only for their phone, is quite common among IT professionals: It's faster, less prone to interference, and in case you mess up some encryption stuff at least you're not broadcasting everything into the whole neighbourhood. All around the better option no paranoia required. But then you have an actual black hat, the type of people who tend to not just wear tinfoil hats but tinfoil underwear, make such a basic OPSEC mistake.

I’m interested in how they got their suspects narrowed down that drastically in the first place.

They listened in on the chat he was in and could glean from chatter that he lived in a particular municipality or something, rough area. Stuff like, dunno, complain that the supermarket is closed because they had a water leak or something and pin-pointing that. The rest was driving around and see if anything correlates roughly, then park there long enough to make that correlation court-proof.