As a scientist you must be aware of two major things, level of confidence and Bias. If a test does not pass a certain bar (95% confidence) it is not considered significant. This idea runs through science, in one form or another. When they say inconclusive results, they litterally mean that that confidence limit was not reached. In more physical sciences they would have to stop speaking at that point, results not significant end. However, as it is about behaviour they will still highlight a few things. They degree to which trends are looked at and depth of analysis are afected by the second thing, Bias. You see, once they decide to look at a result that did not pass the significance test, both the positive possiblity and negative possiblity both have the same same strength, but the one that fits their hypothesis will be looked at (n this case the negative). Hence Bias.
Further, the topic of masturbation and pornography have always caused a massive rift in societies all over the wrold. It is reasonable to think that the people performing these investigations would find themselves wittingly or unwittingly subject to the same rifting.
To sum up, if it is inconclusive then it is not a significant result. As a result, none of the trends observed can be considered more likely than their opposite possiblity. Trying to suggest any one possiblity is more likely would require that possiblity to produce a significant result. Hence discussing such is a sign of intentional or unintentional bias in the investigation.
