I find it oppressive when values are placed on thing and other things are devalued in a political way that undermines another persons experience.
I find the idea that PIV is unnatural by some feminists as a exercise of power. It places those who do value it and do find it natural outside of their group. It is drawing lines in the sand about what is acceptable and what isn't.
So yes, it is oppressive. Even by your own patronising dictionary definition.
To be frank, I regard vast elements of radical feminism as deeply oppressive and deeply conservative and reactionary rather than encouraging free expression and belief. I find it a very prescribed and narrow view of feminism that doesn't believe in liberation values. I mentioned a couple of weeks ago, that as a bisexual I often found feminist thought on this forum very alienating. Julie Bindel's article and this whole business of PIV pretty much sums it up for me.
PIV satisfies one part of me. It comes very naturally. But it doesn't satisfy every part of me. Equally other forms of sex don't fulfil that either and they come very naturally. They are just different, and equally valid. I despair at the PIV business as it completely disregards my experience and the experience of many others.
I don't doubt that PIV isn't right for many people. Whats right for me, isn't right for them. Where I think it is wrong, is for others to make generalisations and say that PIV is unnatural. As if it is right for some then of course its a natural experience. That is oppressive.