It's fun that it abuses ARP's ability to include an arbitrary payload, but just to remind everyone of networking 101, thing that the author is relying on is just the simple fact that switches flood packets addressed to ff:ff:ff:ff:ff to the entire broadcast domain. You can achieve similar message flooding without having to have superuser/raw packet permissions by directing packets to the L3 broadcast address whereupon they will (usually) be L2 flooded (Aka it's fun to ping the broadcast address.)

Using ARP doesn't offer any particular advantage, and I would note since many modern switches do thinks like snooping arp packets, putting a high amount of bogus ARP traffic on the network could actually have some negative impact. It's still fun at any rate and reminds me of the type of crap that I used to make when I was learning. As alluded to before, I personally would have chosen to abuse ICMP for this purpose; maybe it's a future avenue for development. Kudos to the fun project!