Really, get good links for him. I saw sites losing google traffic from penguin where we simply got some good links and they make a comeback.
Although I believe that getting good links to a specific page can overcome a penalty, from my experience good links to some pages on a site - even hundreds of thousands of them, which signify a highly authoritative site - do not help the other pages on a site overcome Panda or Penguin penalties.
It is still easy to ranking #1 in Google if you are the only website mentioning a keyword. I am guessing no one else sells it but they mention it which is why he isn't ranking for these unique products.
Again, from my experience, that is not true if you have a Penguin/Panda penalty. The penalty pushes your page way down, first below the other competing results, then below things like empty results, then below the scraper sites, then below the irrelevant results on authoritative pages, then below the spam that hasn't been penalized yet.
I am speaking from experience here. I have a term which is very rare on the internet because it is about a piece of memorabilia that I discovered that almost no one has. Yet when I search for that item, I see the pattern described above - my page on the item isn't returned until page 2 or lower even though the pages above me are either not talking about the object, or have only learned of the object from my site and offer less information about it. I have a lot of such examples.
As far as information sites go, I am seeing Wikipedia taking up more and more spaces at the top - even though those pages link to my site as one of the sources of their information - to the point where irrelevant Wikipedia results will outrank my directly on-topic page. I wouldn't care so much except that for whatever reason, my site is penalized, so although I may have the 2nd or 3rd most information on a topic (because Wiki stood on my shoulders to build their pages), I'm now in the cellar somewhere.