Remember in your analysis that NSI's whois is *notoriously* inaccurate, and quite often the "owner of record" of a /16 is a service provider, and the person you WANT to send the mail to is the admin of the company that bought a /22 from that provider's /16.
Hint: You ever had a hack-in attempt at your site, and tried to figure out who owned the IP address? How long did it take you? Have you ever come up empty-handed? Good - now design a way to do that look-up several hundred times *a second*.
But yeah, with a little bit of hand-waving, they could get the mail to the right admin at the right company.
This isn't NSI's fault !!! Every ISP that I have worked for that assigned a block of 8 or more IPs properly swipped their IPs with ARIN. If people get lazy and just swip(spelling ?) a /16 instead of individual blocks, ARIN cannot be blamed. Even the IP's for the /25 that I am on on my cable modem at home are properly swipped to reflect the geographic region as well as my MSO.