I believe the point of the article is that the personality that is resistant to change may be useful when this person believes in an idea (free software, privacy, etc). When they are confronted about the idea they will also not be willing to change. Then the ideas can develop themselves to become reality. Of course when this rigidity comes to social behavior this may be an issue.

To go a bit philosophical: I wonder if we can truly be rigid in some aspects and flexible in others. I guess this can be taught.