Having been the Duck a time or two before.....this could be an interesting change if they in fact have "anti-aircraft" weapons. A proper threat analysis compared to flight profiles and take-off/landing paths might go a long way towards countering that threat.
I would not rule out waterborne threats or swamp sites as the Insurgents have a proven ability in riverine ops.
For sure I would not consider the Nigerian Military competent enough to be a serious counter measure to MEND.
Several AK-47's acting in unison close to a landing site is one can of threat but throw in RPG's or .51 caliber machine guns and one finds himself in the Big Leagues very quickly.
That is when one becomes a Duck.