However, It is quite common to get "fossils" containing original organic material...like this "160 million" year old squid ink. They even used some of it to write with a pen - Sea Breeze
Please read the article you linked to. Nobody used 160 million year old squid ink to write anything. Researchers used a combination of very sophisticated techniques to determine if melanin was present.
Other soft tissue discoveries in fossils have been similarly challenging to confirm using very high resolution microscopes to identify collagen and red blood cells. The idea put about by creationists that rotting flesh and oozing blood was found inside fossils is risible.
You can read a very detailed explanation written by an evangelical christian at the Letters to Creationists blog.