[Summoner Icon] Persistent Poros

So the FAQ says the Poro Icons will only have an in-Game effect during Legend Of The Poro King.

Why shouldn't they continue on Howling Abyss?

Why not let them act like when Braum feeds a Poro? He gives the fed Poro a mustache.

If you feed a Poro while you have the Icon up, it gains the appropriate Poro-Skin. Just like they gain a mustache when fed by Braum.