Don't worry about the specific issue being examined. Instead, just ponder those two sentences for a minute. Focus on the word tweet. Is PolitiFact doing self-parody now?
I have a low opinion of the fact-check movement, since the supposedly "objective" fact-checkers are influenced by the same biases that reporters bring to other types of news. For specific examples, see my Manhattan Institute article, which also includes links to some delightful skewerings of the fact-checkers by Mark Hemingway.
At its worst, fact checking is an attempt to control political discourse by defining the boundaries of acceptable speech--all under the banner of objectivity and fairness. Take out the subjective and salacious ratings--"mostly false," "three Pinocchios," etc.--and re-label the pieces as "analysis" or "opinion," and I would have much less to complain about.
In the midst of the 2012 election, I annoyed my friends by sending them this self-written parody of a fact check:
During his convention speech last night, Mitt Romney said that he would be a "great" president. We have called him on this falsehood before, but both he and his surrogates keep repeating it.
The FACTS: Romney never says exactly what he means by "great." The vagueness of the word allows him to twist its meaning in any way he pleases, which is a trademark of dishonest politicians. He is also implying that he can predict the future--an ability for which he has provided no evidence in the past. Strictly from a probabilistic perspective, it is unlikely that Romney will be "great" in any generic sense, since a recent poll of historians labeled just a half dozen past presidents "great." It is possible that Romney also includes the category "near great" within his definition of great, but that has never been explicitly stated, and even if true would not generate a more than 50 percent chance that his prediction will be borne out.
The VERDICT: After the first time Romney falsely claimed he would be a "great" president, we rated the comment just "mostly false," given the lack of specifics provided. However, even after we have called him on the lie, he and his surrogates continue to repeat it over and over. A spurned Fact Checker is an angry Fact Checker, and so we now rate this claim: Pants on Fire!
The most common reaction I received was, "Are you sure that's a parody?"