A player, substitute or substituted player is sent off and shown the red card if he commits any of the following seven offences:

(...)

5. denies an obvious goalscoring opportunity to an opponent moving towards the player's goal by an offence punishable by a free kick or a penalty kick...

That's the rule according to FIFA - nothing about the offender being the last man.

Still - a great game, lots of skill, spirit and energy shown by both sides.