There was an article on BBC sport about this a few months ago. I think the club in question was in Wales and the transitioned female in question was nicknamed 'the beast' by her team mates and often completely annihilated her opposite number tackling them.
I have absolutely no issue with people deciding if they want to transition, whatever floats your boat and makes you happy. However, I have a real issue with them then competing as a woman as this can have a serious consequence. Completely agree that it is for the RFU to step in here and take the decision out of the clubs hands. The issue is, can you imagine the backlash from the bohemian snowflakes about descrimination if the RFU said no. None of whom will ever have played the game or understand the potential impacts on naturally born women.
There is a hurdler in the US who transitioned, was ranked over 200 nationally as a man, transitioned and 12 months later, running slower was ranked 3rd nationally. You will get people who do it on purpose.