Are Rioters allowed side projects?

So with the whole Irelia fiasco going on, I saw the idea that Frostblade should be turned into Winter Wonderland, and a new Frostblade be made. With this comes the question, can Rioter(s) take stuff like this up, come up with an idea and work on it in their free time to be implemented in the game.

Say if one of the skins department people want to remake the skin, on their own time, not interfering with their work, are they allowed to?

Edit: I guess because i am not complaining about Frostblade Irelia I get downvoted to obscurity. Noice