I think that Brandon is probably pretty harmless. Immature, certainly, but I don't think Mikayla is in any danger or anything like that. Brandon is attracted to her, obsessed with her, and going a little nuts out there. I think of it as how we've seen in previous seasons, some survivors go a little crazy because they miss their families, or they're hungry? Well that's how I see this. Brandon's attracted to her, and that, combined with lack of food, poor sleep, withdrawl from family and his regular daily life, is totally messing with his brain. Unless he turns it around, he won't mentally be able to handle being out there for too long.
I believe things are being edited to make him look like a stalker perv. It makes for more compelling TV. I had a friend who went on one of those baby shows and when I saw it aired, my jaw just dropped. They had edited her and her husband to look like their marriage was totally on the rocks. For instance, when the show aired, it showed her saying "I don't know what makes a marriage work." When I asked her about that one, she laughed and said they asked her what the secret to a successful marriage was. She had started her sentence with "I don't know what makes a marriage work... I guess trust, commitment, mutual respect" etc. But they completely left her answer off, as well as them asking the question in the first place.
ETA: Don't get me wrong, I think he is a creep. But I don't think he's the completely psychotic pervert he's been shown as.