[microgood]

His ignorance of his breaking the rule at the time of the transgression and when he signed his card is irrelevant.

Actually you are wrong. According to the article at PGATour.com:

"The decision to assess the penalty -- rather than disqualify Woods for signing an incorrect scorecard -- comes after Rule 33-7/4.5 was changed in 2011 to read that if a player unknowingly signs for an incorrect score he will be assessed a penalty rather than be disqualified."

Woods assessed two-stroke penalty

[BlueStateRightist]

Then any rules transgression can be explained away by the player saying “he didn’t know” after the fact. There’s too much slack there and it opens the door for subjective and inconsistent rulings.