That's not the sort of purity that the article is talking about. The article is talking about purity for purity's sake -- a relative and subjective set of rule

That's not the sort of purity that the article is talking about. The article is talking about purity for purity's sake -- a relative and subjective set of rules that exist to provide levers of power. A singlular and uncompromising focus on OS security serves an absolute and objective purpose, that being... OS security. To the extent that it is objective, it is less subject to being coopted for political purposes.