I wasn't saying you were homophobic Italian and I certainly wouldn't want you to feel pushed out of the thread because I've given off that message. It's just that there is an obvious and inescapable connotation that exists, even if you aren't intending to allude to it, when saying anal sex isn't natural. It reads as a negative value judgement. I accept that is perhaps my own misinterpretation but that is how it is often contextualised. What were you meaning to convey by bringing it up?
why don't you believe the poster was telling the truth? Do you think it is not true young girls get pressurised into anal sex. There seems to be information 'out there' that it really does happen.
That's as obvious a strawman as I've ever seen. No, that's not the reason I don't believe Honky. As with any dripfeed that justifies a poster or deflects from criticism, I am naturally sceptical of this important information that was initially omitted and which conveniently changes the poster's role from unreasonable to reasonable.
Let's face it, her first post was "don't get me going about anal sex, that someone mentioned. I've told my Dgd's if anyone suggests it tell them to eff right off!" When coupled with the "only slags have anal sex comment", which she felt no compulsion to challenge, I think the likeliest scenario is that she personally has a negative view of anal sex (and those who practice it). When challenged on this and her exercising control over her DGDs sexuality, the story conveniently changed to include this friend who has been pressured into anal sex and that the conversation was really about advising them about the pressures they face as young women. From unreasonable to ultra reasonable, yet her first post said none of that. 
Do you really find it likely that a situation occurred where a girl has been coerced into sex and Honky's main issue is with the type of sex act rather than the potential abuse that's taken place, and then to be ok with her DGDs indirectly calling their friend a slag. "Hey Grandma, we're a bit worried about our friend who's boyfriend has been pressuring her into having anal sex even though she doesn't enjoy it. Oh, by the way, only slags have anal sex." Sorry I'm not buying it.