As far as news content goes, unless it is a very heavy news day, the first twelve minutes of all three network nightly newscasts usually provide all the truly important and "hard news" stories of the day.
The first break, at about 6:42-pm, also is past the halfway point in news content for the 22-content-minute program. So, running the unbroken first 12-minutes of the highest rated daily TV national newscast is bringing something worthwhile to WOR listeners who, presumably, can't watch it on TV.
As far as politics being involved in this decision, that is really doubtful. Like almost everything else it likely has to do with money.
As news anchor, Brian Williams is acting as a professional journalist, and appears to make an effort to keep his personal politics out of his reporting. That is NOT the same as Sean Hannity, Rush Limbaugh, Levin or any other biased talk show host, right or left.
Mike Wallace acted as a journalist on 60-Minutes, and was said by some to be a "lefty" and after years and years, people were surprised to find out that he had always been a registered Republican. And his son is now a journalist for Fox. But professionally, as journalists they do try to keep close to the facts, and stay unbiased and somewhere in the middle. If they don't, and instead act as cheerleaders for one side or the other, they lose their journalist creditability.
I enjoy listening to Savage, but something tells me that his days at WOR are numbered. His episodes of biased anger scare off too many potential advertisers, and again, in the end, its really all about money.