Actual quotation from my textbook on 'assessing historical reliability'.
Does that same textbook advocate reading only sources that are from twenty years prior to the events in question, then arbitrarily multiplying their numbers by ten?
You do realize that your methodology here is:
1. Make a claim about the present.
2. Find an article from the New York Times from twenty years ago that does not support your claim, even if that claim were being made about twenty years ago.
3. Say that the New York Times has a liberal bias, so that their refutation of your claim actually constitutes support for your claim.
Using this methodology, it's child's play to prove that the moon is made of green cheese. After all, there are tons of articles from the New York Times in 1994 which don't say that the moon is made of green cheese, and everybody knows that the liberal media is in bed with junk liberal science. So clearly, it follows that the moon is made of green cheese.