So list yourself as the contact (but not the network owner) rather than him.
I see no reason why there should not be some flexibility in the whois data regarding who is listed as a contact for what purpose, the extent of information required for listed contacts, etc.
I proposed a revision to the way whois works that would have been a compromise between APNIC's delisting and the current chaos. You can read it at http://www.arin.net/policy/2004_4.html It would have allowed listing the block itself without identifying the customer unless the customer was willing to handle their own abuse issues. It also would have allowed for researchers to continue to analyze the Internet deployment in much the same way as before. As always, ARIN policies come from the members first, so if people do not want to follow the APNIC precedent but instead want a more meaningful solution, 2004-4 can be revived by someone else. It all depends on what gets discussed on the ARIN PPML mailing list http://www.arin.net/mailing_lists/index.html#ppml and what gets discussed at the ARIN meeting. That means that everyone on this list is wasting their time discussing this. The discussion should happen on PPML where the ARIN Advisory Council are obliged to take note of it. Or at the ARIN meeting itself. --Michael Dillon