I mean who said that is happening? They basically implied Diggle will be with Oliver. KC having her own head canons which probably result her helping during the crossover is not implying any sort of ship baiting. Also this is KC we are talking about, and her answer dont make any sense when you read them through. JH also mentioned Canaries having some sort of story right from the beginning of s8. This show never really baitet with O/L after it was done, and its definetely not going to do it now. Doesnt matter how much KC wants it to happen. All her headcanons about Laurel in s6 and s7 amounted to zero. And honestly anybody who believes they would do that has not been paying attention.