I support your soap box stance. did you sort out your VPN issue.
Depedning on your VPN access method, you might be able to explicitly exclude the "slingbox.com" domain from your VPN client, so the Slingbox pluggin doesnt get routed to you work network which will no doubt block port traffic required for Sling player to work. Also check out proxy setting in Safari as there is a bypass proxy bit in there too. not really a netwrok expert, but check it out.