The people behind this attribution work aren't political appointees. People forget that the overwhelming majority of the public workforce consists of career public servants. If those public servants happen to work in law enforcement, the military, or intelligence, they're much more likely to be Republicans than Democrats.

So with that having been said, and with I promise more respect than this question will make it sound like I have for your viewpoint: what is it, exactly, that makes your doubts about this attribution being politically motivated more credible than the (extremely common) doubts Trump supporters have that Hurricane Matthew wasn't generated by Obama's wind farms to suppress voter registration?