Safety on an Extra point try

Factual Questions
1

I’m quoting from the NFL rules at:
http://www.nfl.com/fans/rules/try

  1. After a touchdown, the scoring team is allowed a try during one scrimmage down. The ball may be spotted anywhere between the inbounds lines, two or more yards from the goal line. The successful conversion counts one point by kick; two points for a successful conversion by touchdown; or one point for a safety.

  2. The defensive team never can score on a try. As soon as defense gets possession or the kick is blocked or a touchdown is not scored, the try is over.
    OK since the defensive team cannot score, I assume the safety referred to in part 1. means the original defensive team is tackled in the endzone in possession of the ball or forced out of bounds or commits a foul in teh endzone while in possession of teh ball. But if the try is over "as soon as the defensive team gets possession how can this be?

The only way I see this as at all possible is something like the offensive team fumbles, the ball rolls into the endzone, and a player on the defensive team deliberately kicks or bats the ball out of bounds in the endzone.