If you have http and https active, and you connect unintended with http, it's a security risk.
So if you disable http, this can not happen.
Do you know what i mean? It's more secure if the non-secure services are completely disabled.
As a workaround, you could just move it to any other port than 80, so that just replacing "https" with "http" won't work if there's nothing on port 80. Actually, port "0" should be valid, it's "any available port" and since the server announces itself through avahi, that ought to work...