During crown prep dentist said the pulp bled and i would now need a rct (#19) before he would put the permanent crown on. is he liable in any way?

No: When a crown is needed, it is most commonly due to an old large restoration, fracture, extensive tooth destruction due to decay or most commonly a combination of any of the above. Decay needs to be removed and if in the process it leads to the pulp, then you will require a Root Canal as indicated.

Decay: Decay that has spread towards the nerve of the tooth compromises the integrity of that nerve. In the process of cleaning out the decay the nerve is sometimes exposed, necessitating root canal therapy. Your dentist is not responsible for the decay or the need for the root canal. Have the tooth treated correctly before the crown is made.

Very common: Once you have pulp exposure and irreversible pulpitis, there’s no cure. The only way to fix it is to have a root canal treatment performed by your dentist or endodontist. It is always a high risk of pulpal exposure during crown preparation.