www.telegraph.co.uk/rugby-union/2019/09/02/rugby-rightly-inclusive-sport-research-disproves-safety-risk/
Sorry for length of post but I thought it was interesting coming from the horse's mouth, so to speak, and I know many posters may not be able to access it.
A paraphrase of the article.
Brian Moore, former England international and sports writer for the Daily Telegraph (which, incidentally is the most pro-women's sports of all the nationals and covers more female sport than any other national) has put, as he sees it, the arguments for and against trans women's participation in female rugby. He is a big supporter of women's rugby and two of his four daughters have played rugby.
He says comprehensive scientific research on the topic is vital.
Main points:
*The issue is divisive and rugby authorities have to recognise how disruptive the issue is and must be taken seriously;
*Rugby claims to be inclusive but this will be undermined if it does not get is policy right on transgender players;
*Despite there being few transgender rugby players the Kelly Morgan story attracted "hysterical comments like:This is the death of rugby";
*Men do not suddenly decide they want to become transgender. It is not a trivial decision, but one taken over time;
*Many comments show ignorance of the fact that there are wide disparities in size, weight and power, not least because of the physical requirement of different positions: this does not automatically make rugby unsafe for smaller, lighter or less powerful players;
*Comments about disparities in size, strength etc. should not be ignored because, left unchallenged, they become accepted wisdom and women's rugby has fought hard to overcome the impression it is not suitable for females;
*Informed decisions are being hampered by lack of scientific evidence: there is little or no rugby-specific evidence;
*Not surprising rugby has followed athletics in requiring trans women to take oestrogen to lower testosterone: problem is that this is not universally accepted and some academics claim the range needs to be 5 times lower to remove inherent advantages;
*They also rightly point out that trans women retain the advantages of denser bone structure, greater muscle memory and overall size with bone density being particularly important as it affects ability to absorb impacts in tackles, rucks and scrums;
*Comments on physical safety: rugby has duty to ensure players are as safe as reasonably practical in contact sport:
*"Until rugby has better information on this safety issue it would be wise to restrict transgender women to playing non-contact rugby.";
*This would be allowed by section 195 of the Equalities Act 2010;
*Women's rugby accounts for a quarter of global playing population and has grown in England by 28% since 2017: these achievements could be jeopardised by just one incident of serious injury or one successful legal action caused by participation of a transgender woman;
*Legally, morally and for the good of women's rugby, World Rugby needs to act now;
The final paragraph in full.
"As soon as comprehensive research shows it is possible to put transgender female rugby players in a position where they pose no greater risk of harm than natal females, they should be able to play full contact and be welcomed into an inclusive sport has had a good record of accommodating lesbian and gay people. Those who still disagree should at least be honest and admit their real agenda is not safety."
I can't work out from that final paragraph whether he is inherently against it and is looking for more evidence to ban it or whether he believes rugby should be inclusive of trans women and is taking a sideswipe at those of us who are against it 
One glaring error on his part is that he seems to think these trans women all take ages over transition and have undergone the full medical procedures (as opposed to being mediocre blokes who want to succeed in women's rugby rather than fail in men's).