Well, I can not recall if this was in previous updates, I dont think that it was:
Dest=84;CompatibleSystemSoftwareVersion=2.3000-;
I am wondering if it is checking that version, against the PS3's version. Way to tell, someone change it and try again! Or If someone would post their FW version, I can change ours to match, and see what happens!
I can confirm that the PS3.Proxy works after you update to 2.30. What it cannot currently perform is the firmware update bypass.
Just replace your local ps3-updatelist.txt with the new content for 2.30 (look it in the post by sbdman above), update your PS3 to 2.30 and the proxy will continue working.