It has been said before - RNG is RNG. There is a pretty large loot table for the BMAH. It is absolutely feasible that it hasn’t come up in the rotation, just as I’m pretty sure there are other items that may not have popped up in that time frame.
It was confirmed that the mount is available on the market and in the unclaimed box just a few months back when you and everyone else were getting their knickers in a twist.
I will also make a point to add that while you can request them look into it, this forum will most likely not net you a response as it’s pretty much a one-way street in that people report, Devs check, but no response here is given.
Hopefully it will be appearing soon for you, but I don’t know that you can get a response any more than what has already been given.