Lenin once noted that "Everything is political".
And, if one is a socialist, it is. It's just one more article of faith.
Leftists define themselves by their politics. It's who they are. A socialist scientist cannot, in fact, be a scientist. His findings will invariably be informed by his politics.
As we have discovered to our dismay in the AGW "crisis"...
I would even say that most leftists define themselves only by their politics and that's another example of ego-gratification.