There isn't a technical reason. The pattern can be, and sometimes is, quite different than what you state. It is the combination of history and evolving ergonomic considerations in play here. Really old bikes had an all-up pattern so neutral was at the bottom or top of the pattern.
There was a government rule established in the US 40 years ago standardizing motorcycle controls for regulated motorcycles, so there are political reasons as well.
But it isn't for technical reasons.
Between first and second is the most logical place to put neutral given that it can easily placed anywhere. Don't forget, you aren't spending time in the neutral position in ordinary driving, so you certainly don't want to find yourself there inadvertently!