Clear written communication (which is a key aspect of good writing, but not, by itself, enough for good writing) and programming are both largely about clearly analyzing ideas and then expressing them in a symbolic system with defined syntax and semantics.
Software development and public policy are both (largely) about solving problems by designing new systems or improvements to existing systems (while this is more the systems analysis part of development than coding, per se, a good programmer is, of necessity, at least a competent systems analyst, and the problem-solving-with-systems aspect, IME, is what makes programming interesting to lots of people in the field; coding is just the means to the ends.)
So, while I don't think those correlations are all that universal, I don't think its surprising that there should be some degree of correlation between programming and writing skill or between programming and interest in politics (particularly, in public policy).
