Barrichello was in the wet, so I feel that is a mitigation. And anyway, Barrichello's chumpery was buried underneath an even greater chump effort.
It is not always easy to compare because there are different situations and CotW is a first-past-the-post system.
Yes, it was a racing incident, and yes, all drivers get them; I feel it stemmed, however, from ill-placed frustration at being behind his team-mate that can be a weakness.
As Brogan said, it is totally subjective, but we all follow our own criteria and on the Teabag Yokel Criteria For Formula One Chumpery Scale, Lewis comes out on top this week. This is not to say I don't think he's the fastest driver on the grid.