[BoomerSooner]

I'll preface this by saying I've never worked FIBA or even read the FIBA rule book. I'm trusting that what is provided by previous posters is accurate with regard to information from the FIBA rules and interpretations. With that said, here is my somewhat legalistic review of this situation:

The challenge is to determine what the rule-maker's intent was when using the phrase "deliberately scores a field goal in his team's basket". The confusion is in the placement of the word "deliberately". Had the phrase read, "scores a field goal deliberately in his team's basket", we would all agree the intent is to prevent a player from knowingly trying to score for the other team. I assume this was the intent and how I would enforce it (i.e. the confused player scoring for his opponent would not be in violation). The problem is that placing "deliberately" before "scores a field goal" suggests the possibility that the intent is to entirely prevent a player from intentionally scoring for his opponent even if he is unknowingly doing so. The aspect of the rule referring to "accidentally" scoring in a player's own basket is not really of any help because it doesn't define what qualifies as an "accident". I agree with the OP that a deflected pass or a tipped ball during rebounding action is what this rule is intended to cover, but there is nothing presented that suggests it extends to the situation at hand to cover a player that intentionally scores but accidentally in his own basket.

Without a prevailing interpretation from FIBA, either interpretation could be supported. As a general custom, I'd say you are left to follow the expectations of those in your local area. If at some point FIBA clarifies this in the opposite direction of what we all believe was their intent, I don't think it would be a situation whereas anyone should feel like they've been wrong for all those years.