I think you’re completely wrong to suggest that people who advocate for trans rights are opposed to cis men or women engaging in gender non-typical behavior. But as always in such cases, it would lead to a much better discussion if you’d point to specific examples rather than “trans activism” in general.

You are right of course that there should be room for men or women to behave in a gender non-typical way without the assumption that they must therefore be trans. I’m skeptical of the suggestion that it’s trans people or advocates for trans rights who are confused about the distinction between being trans and behaving in a gender non-typical manner.

We’re in fact making progress in both dimensions, which suggests that they are not particularly opposed. For example, legal recognition of trans rights is slowly increasing, while we’re also seeing cis men being more comfortable with non-traditional dress or make up (see e.g. Harry Styles).