Calling it a "true lie" implies that there is some intentional misdirection. But we could just as easily conclude that the President genuinely holds a different opinion as to the relative value of phone call audio vs metadata. Suppose the President feels collection of metadata is not intrusive. In that case, his comments are merely a legitimate and accurate statement of his personal opinion, rather than a deliberate attempt to obscure the issue.

None of this is to say that I personally consider metadata harmless. I'm actually rather protective of my data privacy. I'm merely pointing out that the President's stated valuation of metadata isn't an inherently dishonest rhetorical tactic.