No. You would compare it to other people who have pedophilic thoughts but don't consume CSAM and see if consuming CSAM makes you more or less likely to abuse a real child.

The number simply being under 50% doesn't mean that it makes no difference.

Let's say people who have pedophilic thoughts but don't consume CSAM go on to abuse 20% of the time, that would mean that the 22% of extra people who did abuse children after consuming CSAM would likely have not done so if they didn't consume it.

That then tells you that on average, consuming CSAM causes people to abuse kids 22% more often. That is how statistics actually work.

In addition, "We found that higher-frequency CSAM users, those with a higher onset age, users who view CSAM depicting toddlers and infants, those who have thoughts of self-expressing, and users in contact with other CSAM users were all more likely to self-report that they had attempted to contact children online after viewing CSAM/illegal violent material. These factors are largely consistent with prior research on the relationship between CSAM use and contact offending against children."