What do you mean you are fact checking Trump on this?

[melm00se]

13. CNN is establishing

that they are exercising due diligence as it relates to Trump's statements rather than stamping Trump comments as false or lies.

The latter plays into the Trumper claim that the news media is biased.

It is easier to defend against that when they can say "We said we were checking on it. We did. Now we can stamp it false".

That will never sway the uber-Trumpers, it will have an effect on others and move them away from Trump.

While some can petulantly stomp their foot and say "They should've been doing this all along", the reality is we cannot change the past but we can change present which impacts the past.