I guess I wouldn't draw any line per se, there is no evidence that playing violent video games makes people more violent.

In itself I don't see any problem with doing anything in a video game.

I wouln't change my stance even for virtual child porn or using child sex dolls. In itself, I see no problem.

As long as the evidence shows that using such outlets for paedophiles reduces the likelihood of them molesting children (or it doesn't change it).

I don't think this is studied enough or at all, and I think it should be.

There is no real cure for paedophilia, so paedophiles are pretty much trapped. Literally even just viewing the material that they sexually crave is a criminal act.

If there was solid evidence that giving them an outlet for their desires (virtual child porn or a sex doll) reduced the number of actual children being molested, we should allow it or even encourage it.

If the evidence showed the opposite, we should probably not allow it or encourage it (with the exception for offenders with life sentences, at that point no child could get hurt, so no particular ethical problems with the act itself there I guess).

Until this evidence actually appears, I think it's crazy to put people in jail for using these outlets, like these recent cases in the UK of men charged with a crime for having imported a child sex doll into the country:

[URL unfurl="true"]http://www.independent.co.uk/news/uk/crime/paedophiles-uk-arrests-child-sex-dolls-lifelike-border-officers-aids-silicone-amazon-ebay-online-nca-a7868686.html[/URL]

https://www.reuters.com/article/us-britain-crime-doll-idUSKBN1AG1JS

If we were in a simulation sentient beings would still feel pain so it would still be "bad" to cause them pain.

So it wouldn't change my stance. Anything permissible in video games (as long as they don't dramatically increase actual violence committed in real life), but still bad to cause pain to actual sentient beings in the simulation.