Black Flag?

So, why was Kimi not black flagged due to the bit of exhaust that was hanging off? It was a danger to other cars and spectators. It did in the end become detached and luckily flew off into a run off area. What sort of conversation would we be having had it hit another car or become embedded in a spectators head? Seems that the rules in F1 at the moment are not applied clear across the board.
Matt
Matt