True but can you use two of them plus the on board for 11.3kW?
Of course not. But I bought a Supercharger, so I clearly prioritize solving that. (It is regrettable that orders are on hiatus of course.)
Also price is where I see an advantage, if you want the 5kw anyway.
For that amount of power, you're going to find that that's a lot of mass (30lbs per charger) to carry on a Zero. It can be done in principle, but each one won't fit in a Givi side case, the top rack is not suitable for that amount of mass, and I'd feel pretty worried trying to strap even one to the passenger seat of my bike. I throw my PFC2500 into a waterproof duffle bag and strap that to my passenger seat and top case, but the PFC 5000 is two 2500s side-by-side (1.9x weight and volume) and I don't want to strain my arrangement more than it is.
I'd guess that your best bet is to weld a structure onto the frame surrounding the battery to support them. And probably cut down the cooling fins a bit to save a little weight and drag (and align the fins with the wind).
Anyway, you're free to buy it, but if you do, talk to Harlan or them about how to program it, and think pretty hard about how you're going to carry / mount it.