Did you read the article that JKirk posted? It quotes Ratzinger as having said in The Ratzinger Report twenty-some years ago that, “Limbo was never a defined truth of the faith. Personally – and here I am speaking more as a theologian and not as Prefect of the Congregation – I would abandon it, since it was only a theological hypothesis. It formed part of a secondary thesis in support of a truth which is absolutely of first significance for the faith, namely, the importance of baptism. …. One should not hesitate to give up the idea of ‘limbo’ if need be (and it is worth noting that the very theologians who proposed ‘limbo’ also said that parents could spare the child limbo by desiring its baptism and through prayer); but the concern behind it must not be surrendered. Baptism has never been a side issue for the faith; it is not now, nor will it ever be.” (emphasis mine)
Doesn’t really sound to me like he would have needed to be strong-armed into this. Our Holy Father is a wise, perceptive and balanced theologian, and I’d reckon he came to this conclusion without any pressure placed upon him.