I think it is fair to understand it as "if you have to say that you want to feel manly, you aren't"

I think I've read it differently and this was the source of misunderstanding. I understood it as you should do what you feel like doing and not saying others that it's a manly thing to do.

I heavily reject the notion that you or me get to decide what makes someone feel manly

Absolutely agree.

why are we judging men for expressing that they want to feel like a man without asking them what the fuck they mean?

This, I think is the same misunderstanding of mine, I didn't understand that as expressing the fair desire to feel like a man, but as demanding confirmation from others.

Regarding the inclusion, I think you're right and I am just too toxic myself and too pessimistic. I agree that it would be better to create an inclusive environment and try to support everyone and maybe even fix the toxic masculinity in some. This is a complicated task but a worthy one