Infringement risks using free/libre software

A recent article on the IP Info Blog outlined some potential risks for companies using free/libre software in the products they distribute. I have a quick response.

An entity which does not desire to disclose code or otherwise conform to copyleft obligations in products it distributes to others should be able to minimize their risk of infringement by interacting with GPL code using only standardized, royalty-free interfaces (such as POSIX for the Linux kernel). I don't think it would be unreasonable to invoke copyright law's merger doctrine when using header files which implement such an API; there are only so many different ways you can implement such a freely usable interface. This may be an argument Google might employ were it to be challenged for its distribution of Android (with the Apache license) on top of a modified version of Linux (which it continues to distribute under the GPLv2, as it's required to do).

Any other interaction would apparently involve a lot more risk, probably enough to convince such an entity that it should not use code covered by the GPL or some other "copyleft license" at all. I believe that result would not be incompatible with the intent of the authors who release their code under such licenses.