Refs are under pressure from their assessors to implement the rules regardless of emotions attached to a certain celebration - I have no qualms about the ref issuing the card at that time, all he is doing is following orders (which he is under pressure to do) - the FA should IMO just rescind the card now after the event
FWIW Claude Puel said he accepted the card as Leicester City approached the game professionally and he expected everyone else (i.e. the refs) to do the same