You can't "lock" something that doesn't exist.

[Sated]

Locking things that don't exist is possible and does happen. First example pops to mind is Overwatch's Twitch has "locked" emotes that haven't even been revealed (or probably even created) yet as rewards. To debate the terminology, logistics, and ethics of it is just a derailing tactic to try and squash the interest a lot of players have in playing male viera and female hrothgar.

Ultimately it boils down to SE looking at the feedback from players and determining if the interest matches the development time it will take to fulfill the request, as with anything else.