Wigan would find it very difficult to mount a claim that OAFC are infringing their mark, since OAFC could 'prove' that they had been using it before Wigan. In fact, OAFC could probably attempt to oppose the mark on that basis but, since OAFC have not themselves sought such a mark, this would inevitably come to nothing too.
Wigan have no real reason to oppose OAFC's use of the word Latics though, since it would never be used in a manner that would compete with Wigan or attempt to confuse people into thinking that it was associated with Wigan.