Ichigo is not Pure Blood Quincy if you read the chapter it is clearly stated that Quincies are born with the power of Blut and mixed bloods are capable of obtaining it through training. Is it so shocking that because of Ichigo's innate power that he was able to accidentally obtain Blut during a battle? We have seen this type of thing many times before from Ichigo. Also the Holy Selection did not mean every mixed blood Quincy's power was used merely a SELECT few chosen by Juha. If Juha took the powers of every mixed Quincy he would not have a large enough army to attack Soul Society, as it was stated there were so few Pure Blooded Quincy's left, and as we can see with him drafting Uryuu Juha has no beef with mixed bloods. Also Masaki being chosen shows that she was no longer Pure Blooded after being attacked by the black hollow. So if Masaki wasn't Pure blooded how is Ichigo? considering he is also part Hollow and Shinigami.