Lacey is an ass, but, yeah, I would find Shane scary to deal with. He's fine until something happens where he feels slighted or disrespected (whether imagined, exaggerated, or real), and then he brings on the some pretty intense anger, especially when interacting with women. The motivation seems to be "You didn't stroke my fragile ego when I wanted you to, so now I'm going to punish you by acting like a threat to your safety."
I'm sure there were times when Trent felt disrespected or whatever, but he didn't make a habit out of projecting anger. Even when the women were talking about the homesteaders vs. hunters thing (which I thought was a little petty), they were all pretty respectful with each other at a moment that tempers could have gotten out of hand if they had let themselves do that.
You can excuse Shane's behavior by saying he just has a problem with impulse control, but having to deal with someone who is larger and stronger than you (while you are both naked, no less) who has a problem with impulse control can be scary.
But in the end, I think the women just disliked Lacey more than they disliked having to tiptoe around Shane's ego.
Edited to add: And I think the others never forgave Lacey for what she said to Mel to encourage her to tap out. Lacey's downfall was that she didn't understand the benefit to the group of taking care of someone who is down and hurting. A group actually is made stronger when they care for those who are in a weakened state because it builds trust and goodwill all around. After all, you never know when it will be you who needs the others' help (and Lacey did get hit with the karma bus pretty badly on that one in the form of a burnt hand). Also, Lacey didn't understand the emotional benefit of having Mel around even if she couldn't contribute as much physically. Everyone loved Mel. She was funny. She made them laugh. In a harsh situation, you cannot underestimate the healing power of the person who can make you smile.
I'm a cynical so-and-so to the core, but that clip of Jeremy saying, "That's my Mel," and then sprinting off to find her warms my cold heart every time.