This is a teeny weeny bug, probably related to :discourse2: being bespoke or something. It would be nice to have it in the default emoji sets though in other instances. We like and refer to the mothership quite often!
I discovered this when Oneboxing.
It renders nicely here in meta:
But not in mine:
FWIW, I find this idea appealing. 
I just tried a workaround of adding it as an image instead, but that got pulled out as the onebox thumbnail so didn’t really work as well as I’d hoped.
We only ship official Unicode emojis in Discourse, and leave for admins to add their custom emojis easily in the web interface.
No space to slip a cheeky bit of branding in? 
Maybe a special little something for the admin guides, etc?
