Oathsworn are not restricted from using Celestial magic. If you read the packet, we defined it specifically as they would not be predisposed to casting it themselves. But if you have an Enhanced Blade, feel free to cast it on the Oathsworn and let them go to town. If they want to roleplay that they don't like it, that is player agency and I urge them to play that any way they wish. In fact, Oathsworn can now learn and use Celestial magic if they wish, but there will likely be dire roleplay consequences from the other Oathsworn around them.
The only race explicitly stopped from being able to learn Celestial magic is Biata.