Their abysmal Origin of Life brochure (quoted above) is full of terrible 'reasoning'. From just the same chapter as the quote above, they claim (relying on an extremely naive audience with no concept of the periods of time involved) that transitions between species are 'unreliable' because they're 'too close together':
*** lf question 4 p. 23 Has All Life Descended From a Common Ancestor? ***
Let us assume that the estimates of researchers are accurate. In that case, the history of the earth could be represented by a time line that stretches the length of a soccer field (1). At that scale, you would have to walk about seven eighths of the way down the field before you would come to what paleontologists call the Cambrian period (2). During a small segment of that period, the major divisions of animal life show up in the fossil record. How suddenly do they appear? As you walk down the soccer field, all those different creatures pop up in the space of less than one step!
And then, on the next page, they claim that transitions between species are 'unreliable' because they're 'too far apart':
*** lf question 4 p. 24 Has All Life Descended From a Common Ancestor? ***
Specimens placed in the series are often separated by what researchers estimate to be millions of years. Regarding the time spans that separate many of these fossils, zoologist Henry Gee says: “The intervals of time that separate the fossils are so huge that we cannot say anything definite about their possible connection through ancestry and descent.”34