It is certainly NOT true that RN's don't have any training or experience in breastfeeding. I am an OB RN and I have tons of training in helping new moms learn to breastfeed- its what I do for a living! We are the ones that are there for the moms day in and day out- the LCs and Peds just see them once or twice. Just had to get that out of the way.
Anyways it is true that the more your son eats the more he will poop and get rid of the jaundice. I had the same problem with my now 7 month old son, who I am still breastfeeding today. I chose to pump and also give formula when he was jaundice because I felt that was what was best for him, not because of anyone else's advice. As long as you have a good pump and pump whenever you supplement it should not affect your milk supply much. I know it can be very frustrating as a new mom to get so much different advice- it can be frustrating for us as RN's to deal with this also because the mom's don't know what to do. So my advice is to breastfeed for a good 10-20 min each side and then supplement if he still seems hungry (formula or EBM) and pump. Then slowly cut out one supplement/pumping at a time until you are sure he is getting enough (6-8 wet and 4-6 poops a day and 8-12 breastfeedings). We give that plan to lots of mom's going home. See your Ped or a LC if you are unsure! Above all do what is best for your baby and what works for you and your family. Good luck!