I've read the article and it's certainly interesting, but I don't think any of his five "requirements" are in fact necessary, though they're all pretty common.
1. Moving into the home key, and/or an increased focus on the home key.
That's usually the case, but "Pulling Mussels from the Shell" by Squeeze fails this test - the verses are in A minor and it ends in A minor, so that's presumably the home key, but the chorus is in C major. I'm sure I can come up with other examples.
2. Different chords and/or a change in the chord pattern.
Plenty of songs fail this test - "I Saw the Light" by Hank Williams is the first to spring to mind.
3. Different harmonic rhythm.
I'm not sure what's meant by "harmonic rhythm" - the pace at which the chords change? Again, "I Saw the Light" fails this test.
4. Different melodic rhythm
Lots of songs fail this test. In fact many songs have exactly the same melody in the chorus as in the verse, e.g. "The Yellow Rose of Texas".
5. Different rhythmic or temporal placement of the melody.
I'm not sure how this differs from 4 but again "The Yellow Rose of Texas" would fail. There must be lots of other examples.
It's a good question though - what exactly defines a chorus? We generally know it when we hear one, but it's difficult to pin down. It's usually the case that the chorus lyrics remain the same throughout the song while the verse lyrics change from one verse to the next, but by no means always, particularly in comedy songs where you don't want to repeat the jokes too often (e.g "A Song of Patriotic Prejudice" by Flanders and Swann).
Perhaps the best definition of the chorus is the bit that everyone goes out humming