Is it true?
Well, initially, everyone who believes in creationism started with a religious belief, and then tried to make arguments which fit that belief.
On the other hand, every single person I know who questions 9/11 initially believed the government's version of events.* However, once we looked at the evidence of what happened - the documentary, audiovisual, physical, chemical, and historical record - we began to realize that the government's story has more holes than swiss cheese.
In other words, they followed the scientific method, which is the opposite of creationism. Indeed, many scientists followed this exact route in reaching their conclusion that high-level people within the U.S. government aided and abetted the 9/11 attacks.
Similarly, legal scholars are trained to weigh conflicting evidence, and determine which side's story is believable. Many legal scholars followed this route before concluding that elements within the U.S. government are guilty for 9/11.
Many 9/11 skeptics are atheists. For example, Michael Rivero regularly rails against religious dogma. These folks certainly don't believe in creationism.
Many 9/11 skeptics would label themselves "spiritual, but not religious". These folks aren't fundamentalists in any sense of the word, let alone creationists.
Quite a few 9/11 skeptics are people of traditional faiths, either Christian, Jewish, Hindu, Buddhist or Mulsim. But I don't think a single one of these people is a creationist.
The "creationist" label is just another in a long line of false attacks on those who question 9/11. It is another example of government apologists' never-ending attempt to move the goalposts.
*I have heard of perhaps 5 people who doubted the government's version from the start. However, their skepticism did not come from some pre-existing, rigid or dogmatic worldview. Rather, they had been given tips by intelligence officials or others about the impending attacks, and knew they should have been prevented, or they were physics professors who knew that the destruction of the Twin Towers defied the law of physics which would apply to normal "collapses".