IBM is made up of many different employees, and they each have their own ideas, and their own agenda (just like everyone else). That includes the person or group that wrote the article you read. The idea that there is an "IBM" position on anything is a complete total myth.
DB2 LUW dwarfs Informix in terms of revenue, market share, new licenses, R&D, and every other measure one can think of, so your idea is completely and totally ludicrous.
IBM would like see Informix sales rise because right now it is costing IBM more money to maintain it than they get in Informix revenues, and it would be very ugly for the remaining customers if IBM pulled the plug on it (especially since IBM promised several years ago not to do that).
Use it in moderation.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390