That's like saying the keeper has it covered normally. The defender was the last player and the keeper took him out. It's a clear red.
"Where a player commits an offence against an opponent within their own penalty area which denies an opponent an obvious goal-scoring opportunity and the referee awards a penalty kick, the offender is cautioned if the offence was an attempt to play the ball; in all other circumstances (e.g. holding, pulling, pushing, no possibility to play the ball etc.) the offending player must be sent off." The ridiculous double-jeopardy rule. Which means the ref thought the keeper was trying to play the ball, which....erm.
It wasn't in the box though. You've quoted a rule that only applies when penalties restore the goal scoring opportunity.
It doesn't. The whole point of the rule you've quoted is that a penalty restores the goal scoring opportunity so can't be a red unless the player isn't playing the ball.