Why does Thomas Wienandy rely on Homosexualist Arian Rowan Williams for his book "Athanasius and his Legacy?

 https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/r/Rowan_Williams.htm

Homosexuality

Williams' contribution to Anglican views of homosexuality were perceived as markedly liberal before his ordination as Archbishop. These views are evident in a paper written by Williams called 'The Body’s Grace', originally delivered as the 10th Michael Harding Memorial Address in 1989 to the Lesbian and Gay Christian Movement, and now part of a series of essays collected in the book, "Theology and Sexuality" (ed. Eugene Rogers, Blackwells 2002). In the conclusion of this address, he asserted:

"In a church that accepts the legitimacy of contraception, the absolute condemnation of same-sex relations of intimacy must rely either on an abstract fundamentalist deployment of a number of very ambiguous biblical texts, or on a problematic and nonscriptural theory about natural complementarity, applied narrowly and crudely to physical differentiation without regard to psychological structures."

The same year as he made the above comments, and as a practical consequence of the views he expressed, Williams founded the 'Institute for the Study of Christianity and Sexuality' (which in 1996 became the 'Centre for the Study of Christianity and Sexuality') - a group meant to combat homophobia - whilst Professor of Divinity at Oxford University, a fact that had characterised him amongst liberal Anglicans as a significant figure in the effort to make the Anglican Church's moral stance on homosexuality more inclusive.

When he became Archbishop, questions of whether and how Williams would apply his views as Archbishop, specifically as regarded homosexual relationships among the clergy, were put squarely in the spotlight in 2003, through the issue of the proposed consecration of gay priest Jeffrey John as Bishop of Reading. Following protest from Anglican bishops in the developing world, Williams asked John to withdraw his candidacy, but then arranged his appointment as Dean of St Albans, one of the oldest Christian sites in England, in a move that was widely seen as a compromise to maintain the latitudinarian unity of the Anglican Communion.

In a September 2006 interview with a Dutch newspaper, Nederlands Dagblad, Williams stated that "in terms of decision-making the American Church has pushed the boundaries" in its policies regarding homosexuality. Denying that the Church had to accept active homosexual relationships, Williams argued that the Church had to be "welcoming", rather than "inclusive", a distinction he characterised by saying: "I don't believe inclusion is a value in itself. Welcome is. We don't say 'Come in and we ask no questions'. I do believe conversion means conversion of habits, behaviours, ideas, emotions". Moreover, the Archbishop seemed to distance himself from his more liberal 1989 essay, explaining, "That was when I was a professor, to stimulate debate... It did not generate much support and a lot of criticism - quite fairly on a number of points."