lgbt normalization is done for those who aren't lgbt. kids who are either lgbt themselves or have lgbt parents are already aware. by teaching those who aren't aware you reduce the risk of kids being ostracized and bullied. yet you would have that delayed by a few years under the guise of "brain development and ability to retain information", which by the way has very little to do with the subject at hand. doesn't seem like "the opposite of homophobic" to me.
the reason i dismissed your "argument" btw, is because lgbt awareness doesn't require retaining information or building up knowledge like some other stuff taught in school. you could argue that math requires you to have solid fundamentals which if taught too early and not thoroughly enough could hinder further development in the field. similar thing could be said about languages and a bunch of other subjects. it doesn't apply to something like lgbt awareness because it's just that - awareness.
the same ideas could be repeated over and over with an adjusted perspective over the years. a 5 yo doesn't have to be explained about the gender spectrum or sex reassignment surgeries. having children books similar to those shown in the video should suffice (unless you want to claim that a 5 yo is unable to comprehend the idea of a penguin having two dads).
what i perceive #44 to be is you saying that 5-6 yo lgbt children / children of lgbt parents should feel they are different and perhaps be abused by other children because of that, because children at that age can't perceive the idea of lgbt existing and therefore shouldn't be taught about it until they are old enough.