I have been sued for a boat collision that was not my fault. I had my Captain's license at the time.
The rules of the road are the rules of the road. It does not matter if you are licensed or not, you must operate your boat accordingly.
Think about a unlicensed auto driver saying go easy on me because I am unlicensed, and because of that I failed to stop at the stop sign before I ran over those school kids.
Being licensed, however I found to be a benefit. In court I could prove that I had a working knowledge of the rules of the road and had been tested to make sure I knew them forward and backwards. I understood them better the lawyers that were trying the case. Many times I corrected a statement made or was asked to explain how a rule applies in a particular situation. I think it made points with the judge and jurors.
Link to the story
It can happen