The midfielder eventually was loaned to Brentford before the market closed.
"Sullay was the closest out of all the younger players for the first team. I pondered over keeping him – I could have possibly done that," said Pardew to the Croydon Advertiser.
"But of course he wouldn't have started, and there are other players perhaps who might not make exactly the impact he might have made in some of the games we have.
"He's going to have a bigger impact if I let him play and get more experience.
"So I made the decision for the second half of the season maybe to give myself that opportunity, to say 'well, look, go and play these games and let me go with what I've got at Palace'.
"He may have played a few games or have been a substitute to impact it.
"Let's see what happens from now until January and if Sullay does really, really well at Brentford then I will definitely look at him for the second half of the season."