These sort of stories are about all over the place, and not just about Elvis. They're probably made up so no need to think anymore about them. And if they were true, and Elvis was bisexual, is this the end of the world? Doesnt effect my opinion on Elvis.
Think about when these stories came out; Elvis is seen as the devil in human form, he wore very feminine colours, he wore makeup etc there were bound to be 'gay' allegations.