I don't know if the admin reacts following a particular pattern, like a thread needing to be pinned before it can be turned into a board. The Nigerian local board is very active and always on the top of the first page of the other languages board (exempting pinned threads) and is more active than many pinned local boards.

Pinning the thread is however a less demanding request and I hope it gets accepted. As you said it would give more publicity and those Nigerians who may get be unaware of the existence of a Nigerian community could learn of it and join in, giving more reasons to get an actual board.