From what I can tell, there’s not necessarily more. It’s a clear conflict of interest to do business with a source for a story. Doesn’t sound illegal, but certainly gives the appearance of bias.
Publications like the Wall Street Journal have stricter ethical rules than apply in a lot of other situations. Accepting a "yacht ride" would be OK under some circumstances but possibly not in this case--and at least suggesting an openness to business deals could well cross the line as well.
Reuters didn't say he did any business with the source, just accepting a gift ride on a yacht.