I'm very pleased to hear that you have had your rabbit spayed. It is the responsable thing to do! As long as the the cut is fully healed (to the point of scar) there is no problem with a bath. I suggest however that you don't rub soap into that area.

If you are just trying to get the yellow out of the fur around the tail I suggest Hydrogen Peroxide (I should have thought telling you this before!). This way you don't have to bath the whole rabbit and Hydrogen Peroxide is really good at 'bleaching' and removing stuff from fur. Pour the Peroxide onto the area you want cleaned, rub with a soft cloth (make sure the cloth is white or light coloured, Peroxide can draw dye out of cloth and then it will get on the animal), once the area is clean rinse with warm water.

Just as a tip if you ever want to get blood off fur for any reason Hydrogen Peroxide take it right out! Much better than water and not as drying as Rubbing Alcohol.