Possible New Champion in the future with an on death passive

This is probably very stupid, and I am probably wrong, but in the patch notes it says: The shield will now return to Poppy when it kills a champion with a zombie passive (Kog'Maw, Karthus, etc.). Don't you think that maybe they could have just added Sion and Zyra, it takes like 1 and a half seconds, so even though this is stupid it still immediately sparked a red-flag in my head. This may be because they plan to add more in the future. Let me know what you think. Tell me how this is stupid in the comments.