Can a clear glaze be made without gelatin or starch?
Bakery glazes are frequently made with pectin, so that is an option. It would still be a noticeable glaze, though it would be clear and could be flavorless. If you just want the flowers to stick to the top of the cheesecake, it's possible that it would be tacky enough without any glaze. They might just stick to the surface. Alternately, you could use one of the other glazes, but just put a dot under each flower rather than glazing the whole surface.