So basically, shut down Steam completely then run a simple console (e.g., Windows) "1. ipconfig /release all, 2. ipconfig /flushdns, 3. ipconfig /renew"; Not to condone cheating, but this is something that can clog your system if it's having to be constantly checked.
If Steam can access the internet, and be running (to put it plainly) with permissions to install, then it runs as Admin on your stuff -- good luck setting up rules to not have to manually shut down if cheating is something you want to do.
Although, have you seen so-called "cheat" sites? They basically list achievements/trophies for games, because these cheats aren't coded in like they used to be in old consoles. It used to be something fun, I don't know what's happened to the judgement of it.
At the risk of saying too much, is privacy even an issue, really? I was filling out a form today for some website, and it struck me that so many services online have access to our personal information, and copy the same sort of security questions. When you're filling out a form for a new site, would you choose the same security questions and answers if they appear? And, since there are so few "common" security questions, would that be a clue to which question/answer combo you would pick on, for example, a banking site -- given its relative importance to a marginal or third party site (like one for shopping that has your CC info but doesn't hold your actual money). It seems like the more you want to do online, everybody is going to end up with your information. Not really a big deal when you give it some thought. Less stress on you since they won't have to fight eachother over your info, they'll all have a piece, and likely leave you alone. It's like devaluation of the currency of privacy, I guess?
But I digress. Doesn't seem like Valve's changes are that big of a deal - if the old days of button combos are dead, and walkthroughs are plentiful -- then the only cheats that are really out there are console or specific technology hacks that circumvent fair gameplay in a more massively multiplayer world of gaming. To go even further on the privacy bit, why not demand they share it with other parties and see what happens. It would relax controls on gaming companies and you may even get better offers, freeing up the market.
Anyway...