if MLP FIM is to girly, they would not put insane characters or any characters that resembles one of the adult movies like, "The Big Lebowski" there r forms of bronies but non/anti-bronies spot one form and assumes the rest would do the same. there should be a rights for any age for adult to watch something regardless what it is targeting. other then that. turning shows that we watch like transformers into ponys. well not all of them do that, doing that is call "crossover". I would like to turn one of my favorite bands in anime or turn one of the fictional character into "Legend of Zelda Wind Waker" style. There are bronies that make Fan-Fiction for kids to as long it is not inappropriate. If some kid said to adult bronies like
Kid: adults should not be watching shows that's for kids
Adult bronie: by that logic. Kids should not be watching adult shows.
(because some adult shows would be considering inappropriate)
MLP FIM does not show anything inappropriate.
I have known some people watch shows that were might for boys but yet no issue of it. if girls watch transformers they could turn into a girl story if they want to. why can boys just watch MLP FIM make some interesting stories, music's, movies, fan made episodes that can be interesting to fans of any age.
but some bronies may take the show too far.
if u want to catch a person interest, make a fan art that would surely get their interest of the show but don't force them. I have a friend who is a brony and he made fan arts got me wondering why there are adult male watching it or why is it interested. so pick one episode, (Lesson Zero) got my interested since I have watch anime shows that has insane character with their insane face, (like Yami Marik)