I don't feel any particular way about trans Sinclair hcs of any variety tbh. Besides positive-neutral, I suppose.
Generally I hc Sinclair as a cis dude, which is how I most often portray him in my writing. So I'll admit that I've not put a lot of in-depth thought about Sinclair being trans personally, simply because its never been applicable to the ways in which I write him.
However, I have seen other peoples' art and writing which portray trans Sinclair, including transfem, in some very interesting ways that I wouldn't have conceived of simply because that's not the way that I write Sinclair. And I think that kind of breadth of creativity from others done out of love for a character to be shared can bring about a lot of wonderful work.
I guess, ultimately, I'd say my answer to this question is that it isn't really a matter of how I "feel" about the idea (even though I will say I do Not feel badly about the idea in the slightest!). Because how I personally feel doesn't matter. What matters is that I can see other people crafting their own thoughts and ideas about Sinclair's character and sharing those ideas with others which can provide new perspectives and layers to understanding and creating with the character. Or that's how I feel about things, at least.