ORBS is apparently blocking whole /16's belonging to Abovenet only because Abovenet refuses to have whole /16's probed for SMTP servers and then having each such server probed for relay openness. (I can't say as I blame them.)
In effect, Above.net is (by filtering the ORBS probes) licensing every single IP in their /16 to spam via the sordid and detailed means that ORBS works to prevent.
That's incorrect.
This is an incorrect assumption? Please educate me as to how this is the wrong way to view this.
Abovenet, like many ISP's, has a far-reaching antispam AUP, and aggressively disconnects customers of theirs who spam or who allow their own downstream customers to spam. On their main web page (www.above.net) I saw a link with the title "Anti-Spam Policy" pointing to http://www.above.net/anti-spam.html which begins: AboveNet's tolerance for spam originating from our customers, or from our customers' customers, or for spam advertising web sites of our customers of our customers' customers, is zero. Anyone who thinks that a network which refuses to be probed by ORBS must be a hotbed of spam is failing to understand the same property rights issues which spammers themselves fail to understand. Whenever I see a port scanner on my own network I locally block it since it is after all my network and I reserve the right to carry, or not carry, any traffic I want (or don't want). Abovenet seems to be exercising their property rights over their own network. According to reports, they asked ORBS to stop running their SMTP port scanner on Abovenet's address space, and ORBS refused. Abovenet's only recourse was to block access to ORBS' probe host. And so, "I can't say as I blame them."
I am under the assumption that the said block on Above.net/16 didn't go into effect until ORBS itself was blocked - thus the resulting block on Above.net.
That part is correct. Only the motives you impute Abovenet as having (see above text) are incorrect.