What initially strikes me about what you pull out, here, is the need for all concerned to define m/m relationships along the lines that make sense to them/make their opinions seem acceptable.

That's a very good point. It also ties in with the thesis of the Buckton book, which explores the idea that what you don't say speaks as powerfully as what you do. It's those things that live between the lines, between the pages and (sometimes) between the sheets.

Wilde's formulation would, I think, have had the benefit of being familiar, if not necessarily acceptable, to the educated British elite. Due to the culture's focus on the classics one might have had an idea of what "Greek love" meant, in its more abstract and idealized forms at least. Today of course such a formulation might almost be more risky, due to the dangers of running into the whole homophobes-equating-homosexuality-with-pedophilia thing.

As for Stead, I'm not sure whether he was actually advocating for non-sexual homosocial comradeship (call it "bromance") or whether he was more worried that sexual male/male love might no longer have the cover of being viewed in those terms. I'd guess the latter, given that he was writing to Carpenter, but I don't know anything about his own background.