I personally don't think there's absolutely ANYTHING wrong with having taught about LGBT rights at school because at the end of the day they are HUMAN RIGHTS! And everyone should be made aware of them whether they're religious or not.
I am a Muslim teenager myself who am also at a point in life where I am having difficulty with my sexuality...
And like someone mentioned earlier it's comments such as "you cannot be Muslim and gay" that make it difficult for people like myself.
I understand other religions such as some orthodox Catholic parents may also not want their children been taught about LGBT rights but, if schools can teach RE they surely should be able to teach students about human rights. I feel some orthodox parents may feel that by teaching LGBT rights in school it will somehow "turn" their children into something other than straight. Which I know is ridiculous but these are some of the thoughts of parents who are quite traditional.
Yes, Islam encourages teaching the values of kindness and honesty but the teaching of LGBT rights in my opinion should not be ignored because they are equally as important.
As by being taught about acceptance from an earlier age, it will allow young individuals to grow up to become more open minded people and it can help to maybe even reduce the number of people being homophobic/islamophohic in the future
At the end of the day we are all humans, and if we do disagree with someone's else's behaviour we are no-one to judge, let God deal with it in the hereafter.
I believe there's only one type of race and that is the human race!