Yes, provided that the server accepted the second key the rest would not be sent. However, the server can simply respond that each key is incorrect (regardless

Yes, provided that the server accepted the second key the rest would not be sent. However, the server can simply respond that each key is incorrect (regardless of if it is or not), and then get all five keys. Once SSH has ran out of keys to try, it tries to move on to other authentication methods. The go app he has written then automatically accepts the connection at that point, once it knows it has seen all of your keys.