Boy o boy, what Pandora's box did we open up here? Firstly, loreen, you misunderstood my sentence about mustache, etc. It was rhetorical, pointing out to tpe the irony of the foremost Jack loving fan calling Jack too soft/feminine to be the iconic cowboy. I put those words in quotes, to emphasize that I was quoting tpe, in his usage, not of my own meaning or intention. You can read Tammy's post, who understood, and reacted as I did, but said so more beautifully and,

shall we say, emotionally?
I won't dwell on the stereotypical ideas of masculine and feminine, although one can argue the archetype of male and female in the collective consciousness put cowboys, especially the iconic strong silent stoic cowboys in the extreme end of the masculine spectrum, while the rodeo cowboys, with flair and show, drawing attention to themselves, and Jack's exhibiting empathy and tenderness in SNIT, after the bear incident, would put him closer to the feminine end, but I wouldn't move him much further than a tiny bit.
Returning to the topic of fear of love and the iconic cowboy, and tpe's idea of subversion, it occurred to me that if Ennis is the embodiment, the epitome of the iconic cowboy, then it is hardly likely that he was also subverting the iconic cowboy, or himself.
I looked up the word "subvert" in order to be certain that I understood it correctly:
1. to overthrow (something established or existing).
2. to cause the downfall, ruin, or destruction of.
3. to undermine the principles of; corrupt.
Origin: 1325–75; ME subverten < L subvertere to overthrow, equiv. to sub- sub- + vertere to turn
Related forms: sub⋅vert⋅er, noun
Synonyms: 1. upset, disrupt, undermine, overturn, sabotage.
I don't think Ennis overthrew the concept of the iconic cowboy, but rather, extended it to change the world's understanding of the icon. Instead of the romantic idealized cowboy without feelings, Ennis, as Heath portrayed him, took on the human dimensions, and made real with feelings and emotions. This "hidden" dimension was not new, but always there, but repressed and/or suppressed by the cowboy and/or society.
As Annie Proulx said herself concerning the origin of the Brokeback Mountain story, she was inspired by observing these old bachelor cowboys in a rural western bar, looking at the young cowboys playing pool. Then there are those real life stories from letters of people to Annie Proulx after they watched Brokeback Mountain, and told her that they were watching themselves on the screen, of their own cowboy experiences, or someone they knew.
I agree with you that Brokeback Mountain and Jack subverted the old idea of the iconic cowboy, but because Ennis WAS the iconic cowboy, I rather think that he simply showed us the hidden dimension that we didn't know about. The old iconic cowboy was still true, but incomplete with a hidden side, the side that Heath in his genius showed to us, through Ennis.
And to bring it right back to fear of love, it was not only the homophobia that Ennis was hiding, it was also his fear of love and being loved that he hid all 'em years, ever since that first time in SNIT when he loved being held by Jack, when he loved holding Jack, when he sat in front of the fire, fighting the desire to experience love with his fear of love. Out there on the mountain in the middle of nowhere, his desire won, but sooner or later, his fear returns.
Only at the end, when it was too late, when there was no more need to fear, when his one true love was forever denied him, that he could embrace the love that he feared. Ennis could love only in the dreams, in memories, without the real love of his life to be there. Even sharing the love that he still had, with Jack's Ma, and with Alma Jr, it was a love at a distance, not sharing it in his trailer, up close and personal. That is still the iconic cowboy, riding off into the sunset alone, into the distance.