The analysis forgets the very first problem after someone is killing criminals visibly: Light relies on TV to find them. You could tell it's Japan without doing any math about time zones or anythING, as TV itself brings in the bias. To pretend you are elsewhere, you have to be consuming foreign news to even begin to have a chance to hide yourself
Less than a quarter of the way through the article:
> Worse, the deaths are non-random in other ways—they tend to occur at particular times! Just the scheduling of deaths cost Light 6 bits of anonymity
Have you seen the show/read the manga? That's precisely the first tactic L uses against Light - he broadcasts that he has precise knowledge that he's somewhere in the Kanto region of Japan based on this timing. It's also mentioned in the article which you claim forgets to cover this.
At the end of the article:
> Selecting criminals could be based on internationally accessible periodicals that plausibly every human has access to, such as the New York Times, and deaths could be delayed by months or years to broaden the possibilities as to where the Kira learned of the victim (TV? books? the Internet?) and avoiding issues like killing a criminal only publicized on one obscure Japanese public television channel. And so on.