I'm very sorry to hear of this accident...
Did you use a dish washing product in warm water? This is usually what is used to remove thick oily substances off feathers.
And after carefully washing up and avoiding contact with the eye, ear and beak/cere areas, it's important to remove all traces of the washing liquid in order to avoid the budgie from ingesting the product while preening the feathers to dryness.
How long ago did this happen?
Given the very scary ordeal he has been through, it's natural for him to be upset and stressed to the point of not wanting to sing or eat.
It would be good to monitor him for a while and see if he settles in for a restful night of sleep. Keeping him warm and covering the cage for the night should suffice. You can also put some music on low volume to hopefully help him out in diminishing the stress levels.
In order to avoid these types of accidents from happening, it's always best to have the pet birds safely on their cages while we are on the kitchen area preparing meals.
I hope your Bubba will perk up soon, if tomorrow he doesn't seem well, then it would be best to have him examined by an avian vet specialist.