...For sure the CSA is part of the story, but its not the whole story and it doesn't have to bleed into every story. Injured and wounded yes. But not so damaged that the bleeding can't stop.
i don't disagree with the premise of your post grant. i'm adding --what i think-- is another dimension to the larger problem.
an issue, perhaps, society in general doesn't like to talk about or think about or dare i say ever experience: ''life alone.'' we favor and even encourage partnering up, correct? if you aren't dating, good grief even just bagging someone in some circles, on a regular basis you just don't cut it in today's world.... i'm generalizing, but it is what i've come to understand. if we can't even attract a simple date, what does that say about everything else in our personality? what other flaws lurk?
and this isn't about "having to have someone to be whole" or being unhappy alone - i think we all understand the difference for being happy alone is a key to being happy with someone else too.
so, how did someone who does have his act together get to a stage of "life alone"? well, there is the larger problem to solve.

i'm saying that sexual abuse may have played a MUCH larger role in this, for me, than i previously thought.
and there are multiple caveats. right? its not just one time rape: its the rape, which led to a personal dilemma which festered and caused more trauma in my teens; which in turn cause bad decisions, which in turn created a life of chaos in my 20s -- at the height, i think, of when we acculturate with others in the gay community. 30s? well, when i was at that point people in the world around me were partnered. 40s? sadder state of affairs. lol.
but all fingers point to the rape -- not what the church, parents/family said about gays. its not even society's view on gays that makes me type what i have.
now, not possible for me to understand your friend's example without knowing him. but i can ask you this: what support have you given him in terms of creating a "vibe" -- or a more attractive vibe, which in turn helps him to be more attractive to a mate? if not you, what has the "gay culture" done to help him...?
harder question: what has the gay culture done to help...anyone with important issues? me? my answer is simple: "nothing," nothing at time of rape, nothing at time of recovery, nothing in the present when i need gay networking to help me with a job search before i lose the present one ''for being gay.'' lights are out in the gay department on helping others with real, genuine, life-surviving needs..... in my experience.
i do not view these issues as bleeding to death from a wound that healed decades ago. it is something else. i don't know the appropriate word/phrase that captures the mood.
a sum of experiences - yes, perhaps, in part. and i think that sum has to be an exact figure - a matching figure - if you will with the acceptable norms, whatever they are! vary from the "norm" - and ye shall live life alone.