Just going to comment that I saw these mounts added to the game last week, and with the red and white color scheme I thought MAYBE they would be tied in with the Christmas event in-game. Instead they are using them for seasonal colors in the mogstation store.

Now maybe they didn't want a repeat of Halloween, where the broom mount was datamined a month early, and Yoshida has said that 3.15 will be before Christmas, so maybe they will add something before then... but as of now, there are NO new mounts, bardings, or minions added to the game for the seasonal event. There are only housing decorations, santa beards, and reindeer outfit pieces (the old costume looks to have been split into separate parts).

I don't want to sound selfish, and I hope I'm wrong, but it does look like they are prioritizing mogstation over in-game event rewards.