"Our CIO is convinced that technical support for any product is worthless"
Has your CIO ever supported an application environment that included: Oracle RAC, DB2, Weblogic, OSB(aka ALSB), Websphere, Websphere Commerce, or heck a computer?
I would advise in creating a Risk Assessment (aka CYA Signoff) that outlines the risk HE is assuming by not purchasing support. Get his signoff on the Risk Assessment. You'll be surprised how quickly higher ups change their tune, when they realize their decisions are actually documented, and they can't just toss some lowly admin under the bus when it takes hours to recover from a production outage. When you do a Risk Assessment, schedule a meeting with the parties involved, DB Team, Networking, etc. If you can invite a Business side guy, even better.
I know it sucks! I like fast moving companies, that make solid decisions... but sometimes you have to play the game, to avoid catastrophe.
Normally, I would say this will help, in this case, whereas your CIO is against all support, it will only CYA when you have an outage during production hours, and the CIO tries to lay the blame on you.
I'm not familiar with your environment, so unless this project is a smallish LAMP wiki for internal use, I would be concerned.