Trundle's E interupting Recall and Teleports

I was unfortunately in a Bot game recently with a troll on our team (in more ways than one). I was surprised how much he was constantly and purposely using his E (Pillar of Ice) on us to interrupt our recalls and teleports which made the game very difficult for us to work around. I do not know if this is supposed to happen in terms of being a possible bug, but I still feel it's potential for unsportsmanlike conduct, even if it was just a Bot game.

Do you think this is a bug? If not, do you think it should be allowed? (In the case of Trundle casting E on his own teammates)

Thanks for the feedback TheBobbKat