Lugh, while challenging something you've said is like challenging Geezmeister, in that I usually discover later that it was me that was wrong. Even so I have to say that I believe you've misunderstood Tor's methodology.
A true firewall isn't going to help much at all by itself. An anonymous proxy server with an encrypted connection will work but you have to trust the person running it. Another concern is that SSL has been broken, so it's not so secure any more. Tor doesn't need to encrypt the data (although it employs SOCKS) for the reasons partially explained below.
Here's just a little bit from their website:
https://www.torproject.org/overview.html.en There are illustrations on the website that makes a lot of the following easier to understand. There are also several scholarly discussions on the capabilities and limitations of Tor and the accompanying software. I would encourage anyone who has a problem of the type we're discussing to look for themselves at the available information.
"A basic problem for the privacy minded is that the recipient of your communications can see that you sent it by looking at headers. So can authorized intermediaries like Internet service providers, and sometimes unauthorized intermediaries as well. A very simple form of traffic analysis might involve sitting somewhere between sender and recipient on the network, looking at headers.
"But there are also more powerful kinds of traffic analysis. Some attackers spy on multiple parts of the Internet and use sophisticated statistical techniques to track the communications patterns of many different organizations and individuals. Encryption does not help against these attackers, since it only hides the content of Internet traffic, not the headers.
"The solution: a distributed, anonymous network
"Tor helps to reduce the risks of both simple and sophisticated traffic analysis by distributing your transactions over several places on the Internet, so no single point can link you to your destination. The idea is similar to using a twisty, hard-to-follow route in order to throw off somebody who is tailing you — and then periodically erasing your footprints. Instead of taking a direct route from source to destination, data packets on the Tor network take a random pathway through several relays that cover your tracks so no observer at any single point can tell where the data came from or where it's going.
"To create a private network pathway with Tor, the user's software or client incrementally builds a circuit of encrypted connections through relays on the network. The circuit is extended one hop at a time, and each relay along the way knows only which relay gave it data and which relay it is giving data to. No individual relay ever knows the complete path that a data packet has taken. The client negotiates a separate set of encryption keys for each hop along the circuit to ensure that each hop can't trace these connections as they pass through. "
PP
TOR can't encrypt the connection between one's computer and the TOR service, that must be protected by SSL or by means of another proxy service such as those at Privax which will hide that data from keyword filtering even without SSL 
It's rather doubtful that Conroy and Benson's firewall will even work very well, but members that will be affected need to understand the technology well enough to evade it if they wish to continue to be able to access sites that are deemed inappropriate 
Connecting to the internet via wi fi uisng TOR and Hide My Ass will defeat a keyword firewall in my humble opinion since it's worked when TOR alone wouldn't 