Brett acted like an idiot, but the actions of the umpires, and particularly the American league, were pretty bad.
The rule regarding pine tar had been on the books for years, but had never been enforced. This in itself is a serious problem, as it allows for this kind of incident at potentially crucial time.
An exact parallell exists in 1908 with the Merkles Boner incident, which wound up costing the Giants the pennant.
The league acted idiotically in not backing up the decision of the umpire crew, which was, according to the rules as written (though not normally enforced) absolutely correct.
Let me walk my wits here for a moment. In any totalitarian state there are hundreds of rules, governing many aspects of life and behaviour, many of which are not enforced regularly. Then one day a police captain, Gestapo agent, or army officer gets out of bed with a hangover, and bang, you've just broken 20 rules. The essence of a responsible state is legitimate rules enforced with an attempt at equity.
To return to baseball, it is, to my thinking, extremely unwise to have rules that are not enforced, because it allows this kind of gamesmanship, or arbitrary choice of enforcement.
There currently exists in baseball a situation rife for a similar, and possibly worse incident. The rules clearly state that a fielder (including the catcher) cannot impede the runner or block access to the plate or base without possession of the ball.
Now watch a major league game some time and watch a play at the plate. It is common for catchers to set up five feet down the third base line and wrestle the runner until help arrives, or allow them to touch everything in the stadium but the plate.
Its another outrageous moment waiting to happen.