This situation happened in a Shatter I was playing in today. We (Adders) lost control of our outpost to the Maelstrom and came back to recover it. We managed to clear all their members, but at the same time, about the same number of Flames came to claim the outpost.

What happened was Adders and Flames fighting over the outpost with no Maelstrom in sight, but since the numbers were about equal control did not change.
It remained with Maelstrom, giving them free points. At the very least, it should have turned neutral and remained there until the fight between Flames and Adders had a victor.