But Staunton's No 2, Kevin MacDonald, says the Republic are prepared to "take the risk". He added: "If Steve feels he is the right man to play on Saturday then he will pick him."
The FAI are confident that they have a watertight case and say FIFA told them last October they were within their rights to pick players with dual citizenship.
Gibson made his debut in 2003 for the Under 17s but a year later FIFA tightened qualification criteria. The FAI say Gibson's competitive debut preceded that change.