Arguing against using public IP space

[Jason Lewis <jlewis () packetnexus com>]

I don't want to start a flame war, but this article seems flawed to
me.  It seems an IP is an IP.

http://www.redtigersecurity.com/security-briefings/2011/9/16/scada-vendors-use-public-routable-ip-addresses-by-default.html

I think I could announce private IP space, so doesn't that make this
argument invalid?  I've always looked at private IP space as more of a
resource and management choice and not a security feature.