I'm doubting things are what they seem. What matters in this case is based on ASEAN agreements which state a forward ticket is all that is needed to another destination. Expecting it to be a return to home country ticket would NOT go over well with the ASEAN agreements because the real purpose is those countries sharing the tourists between themselves for extra along with many tourists flip between many different Asian countries on sort of a Asia tour and this would really damage the tourism industry with the Philippines as a stop.
I'm thinking it was a seriously overly zealous immigration officer or one trying to suggest a bribe to help pad his own pocket.
There are a lot of zealous immigration officers who don't follow official policies or laws to push what they personally think and some of those officials in immigration put forth illegal policies as well. One of such is when they refuse to let a Filipina travel abroad because they cite the chance of abuse or other bad things. Its not in their legal power when someone has a passport and a ticket to stop them because what nonsense they fear may happen.