I don't know about r/humanism, and US/UK humanists, and those organization like mentioned in article (BHA).
But personally I was thinking that humanism is not just about critical thinking, reason, and life without religion, but also about this idea, that people, and their well being, freedom, happiness is most valuable thing. I was thinking about humanism as about opposition to ideologies that put nation, ethnicity, state, etc above individual people and their well being. An opposition to nationalism/tribalism, right wing political views. As socialism or communism, but without this questionable baggage about class struggle, and revolutions (which are both not necessary good for humanity, and can be again, tool for dividing people, and excusing evil things with some 'greater idea'), and without putting ideology itself above individual people happiness and well being.
And if you really go and read some of these people, which photos you have above on r/humanism, I think you will find similar sentiments.
So from this point of view, in my opinion, author of this article just don't understand humanism.
In my opinion, humanism is more political ideology, and it's important, because just atheism, and skepticism, and pro-science - doesn't say anything about political views. You can be atheist, skeptic (kind of, in some aspects), pro-science, and still be someone who support some right wing, or nationalist views, etc.
Unfortunately, looking at r/humanism, looking at skeptic/atheist/humanist community on the internet, I have doubts that many people share my views, about all this. It looks like everyone want just fight religion (which is good, i support this fight, but it's not only enemy of freethinkers) and some anti-scientific bullshit, maybe also racism little bit etc, but don't want to acknowledge nationalism/tribalism, and similar stuff, which are also irrational and harmful. But this is strange, because if you go and read Carl Sagan for example, you would see that he also didn't liked nationalism/tribalism, and have some specific political views, basically idea of pale blue dot, is that we are just humans, on this tinny planet, and all these borders and division into nations, and all these conflict are bullshit, and we just need to learn live in peace together.
So maybe author of article is right in some way, if community and all these associations don't want to take more clear and more hard political stance, and declare more clearly their humanist political views =)
But in any case, i think author missed this part of humanism description from BHA site, that show that it's not only about "reason vs religious/superstitious beliefs":
makes their ethical decisions based on reason, empathy, and a concern for human beings and other sentient animals
a commitment to the perspective, interests and centrality of human persons; a belief in reason and autonomy as foundational aspects of human existence
Humanist ethics is also distinguished by placing the end of moral action in the welfare of humanity rather than in fulfilling the will of God.
That man should show respect to man, irrespective of class, race or creed is fundamental to the humanist attitude to life. Among the fundamental moral principles, he would count those of freedom, justice, tolerance and happiness