It is not silly at all.
Just as every image in Godard is suffused with his desire for women, so the images of Michaelangelo/Visconti/Leisen are suffused with their desire for men. Whether or not the concept of sexual orientation existed in whatever century is irrelevant: what is vital is whether or not the desire to suck cock was there and if this cocksucking desire is manifest in the aesthetic experience. Worrying about whether we can call Michaelangelo a homosexual or not is just so much academic folderol.
Brian