The hint was referring to these two clues:
- Maurice's package cost 1 dollar more than Neil's package.
- The package with the basketball in it cost 1 dollar less than the package with the computer in it.
What happened was that there was a relationship already on the grid either with Neil or with the basketball (or with both) that was used in developing the hint you received. So for example (this isn't from the puzzle, just a random example for elucidation), if you had Neil = baseball on the grid, those two clues would be saying that Maurice was $1 more than the baseball, and the computer was $1 more than the basketball. Since baseball and basketball are in the same category, and Maurice and the computer were both $1 more than each of them, Maurice couldn't be equal to the computer.
Our hint system doesn't always go into explicit detail on how each of the relationships on the grid interact with the clues - there's only so much room for an explanatory hint on the page. But that's the crux of what was happening here - the hint was correct, it was just taking another true relationship from the grid into account (like Neil = baseball) when formulating the hint text.
That said, we may be able to improve that in a future upgrade so that it can provide more explicit detail.