From my experience SORBS has been run by unprofessional, unfriendly and arrogant individuals.
Some time ago the mail server of one of Australia's largest ISPs was blocked. When I received some of my emails back I followed the instructions how to request SORBS to remove the block on the IP address. I should have never followed the SORBS instructions because I only received a threatening an offensive email back with false claims that I would be running a SMTP server myself to send spam. They threatened to force my ISP to cancel my internet account because I would be abusing their services although I didn't even have a clue how to setup a mail server, nor did I have the hardware or even the provision through the ISP.
When I contacted my ISP they requested me to not respond to the SORBS email because they were worried that their server would become permanently blocked.
Even if SORBS staff are volunteers, I consider it absolutely inappropriate to make false accusations and to threaten the ISP just because a customer followed the SORBS instructions in a returned email.
Thinking back, the whole thing might have been caused because I got one day a dynamic IP which had been previously used by a spammer but regardless of the circumstances, each case should be handled professionally without unreasonable threats to affected customers of an ISP.