The answer to a problem no one had, or a great idea?

[Mr. Dazzle]

And how does the bike know it's doing 6mph if only one wheel is spinning? Which one does it believe?

[.....]

I would imagine that unless you possess the talents of Toni Bou, or regularly do burnouts, but ride normally, then once both wheels have registered a calibrated signal to the ecu, all is well.
But in answer to your, possibly rhetorical, question, it doesn't believe either wheel, hence the eml.
But you probably know that already