Slippery Slope Fallacy. It's the same thing as saying Doom and Grand Theft Auto train school shooters, or marijuana is a gateway drug to hard substances.

This is not me defending paedophiles, I'm just pointing out the flaw in the logic here. Nothing says that having access to these dolls increases the likelihood of them carrying out their desires on a real child, or that by not having access they would never take that step regardless.