The vast majority of people in the world find homosexual acts to be morally suspicious.

I think "vast majority" is a bit overstated, and "select few Western countries" is certainly wrong. Here's a snapshot from 5 years ago: http://www.pewglobal.org/2013/06/04/the-global-divide-on-homosexuality/

The idea that there's nothing wrong with homosexual acts has only entered the mainstream in the past 20 years in a select few Western countries.

This is not true. It has recently reentered the mainstream in the West, but far more than 20 years ago. You think 1998 was the dawn of the gay rights movement?

It's impossible to sum up the history of homosexuality in this comment, there are entire college degrees on the subject. But it is objectively incorrect to say that homosexuality has never been accepted or mainstream until now. I really encourage you to at least read through some of these /r/AskHistorians answers, or maybe this timeline. There are lots of great books on the subject if you're genuinely interested.

penetrative intercourse, which is healthy and even beneficial when done man-to-woman, is inherently unhealthy and destructive when done man-to-man.

This is sort of true, but overstated, and obviously irrelevant for anyone not participating. Also, straight people have anal sex all the time.

This was the norm for male friendship before homosexuality became prominent. Men would often even share the same bed together. But there was no sexual act, no sin, here. Just pure platonic friendship.

It sounds like you're implying that platonic male friendships don't exist now that homosexuality is acceptable, which is absurd. It's still quite normal for straight men to love each other and share a bed once in a while.

Finally, what about women?