Is the only reason these two are shipped because of the height difference?
yes the answer is yes
Like most crack rwby ships, you can't go wrong with height difference + interesting color schemes+ creative dessert inspire ship name because Neopolitan
The "Opposites Attract" trope may also be part of it as Neo is small, quiet, and ladylike, while Yang is tall, loud, and brash., but I don't really see how they could form a relationship in any way ( other than smut which I'm guessing is most of what Baked Alaska fanfiction consists of)
Fun Fact: The ship name, Baked Alaska, comes from the dessert that involves baking ice cream (which from personal experience is VERY difficult to make)