Is Mecha Zero Sion going to be released until tomorrow?

The Mystery Gift promotion is going to last only until tomorrow, so I wonder if Riot is holding off the release of Mecha Zero Sion for after the promotion. It would be a shame if they did that, I really wanted to buy this skin for the Mystery Gift promotion. This skin is really amazing but if they don't plan releasing it until tomorrow, then I will just buy another legendary skin, as I want that free Mystery Gift way more.

I was reading this Reddit thread: https://www.reddit.com/r/leagueoflegends/comments/4e7uar/are_riot_holding_back_mecha_zero_sion_release/

They say Riot explained this skin will not be released untill it is over, but I can't find the source for where they said that.

EDIT: I've finally found it: https://www.reddit.com/r/leagueoflegends/comments/4dsaj4/welcome_to_the_new_age_of_security_program/