Your agument doesn't really hold up. I know what you're getting at, but it's way more complicated than that. Picture this scenario:
A 50 year old hardworking father of two with a wife and a steady job. Is shown respect, handles his business, is the head of the family and has done well for himself.
A 18 year old gangly teenager with no job history, no authority and no self esteem.
Who is more masculine? Who has the highest Testosterone? You'll find that these two do not match up.
There's no doubt that testosterone is relevant in some way, it is after all the primary male hormone, but it's much more complex than that. Masculinity is defined in part by society. Confidence, self belief, self efficacy, autonomy, respect, ambition these could be defined as masculine traits. But so is diplomacy, being knowledgable, being a provider, taking responsibility, being supportive, lending other people a hand and so on. This is just within our current society, and again it's completely different all over the world. Saying that "testosterone" is all that matters and then adding to that, that you could actually tell just by looking at someone is far fetched. It's too reductionist.
That guy in your picture. If he's confident, supports himself, has drive and doesn't care what others think that could be defined as masculine traits for sure.