People have had the ability to cheat in every Civ3 demogame. Some do, and we need the moderators help to clean up. Most don't even though there a plethora of tools like PowerBar, savegame editors, and anyone can write code to find out anything they want given time and a little ingenuity.
The in-game no-cheat mode plugs a couple of serious holes. The most important one is that you can't launch worldbuilder from the middle of a game to find out what's going on, add or subtract things, change the landscape, etc. It also keeps you from having a modded advisor panel which shows all enemy military, or details of enemy cities, or other things which are easily possible in the Python code.
Unfortunately no-cheat won't eliminate the easiest and most prevalent forms of cheating. If someone really wants to affect the DG, he/she can just get elected DP, play offline, and then start manipulating the RNG by reloading after losses and reordering battles, the same as in Civ3. Another way to make a big difference is to load up the initial save and start playing ahead. Don't be stupid and get all-seeing all-powerful foreknowledge, just learn enough that your opinions are always right, and see how easy it is to get elected the next term.
We can't avoid even the most basic of cheats using the no-cheat option. What then does it boil down to? We have the option to allow an incredibly useful ability to log everything which goes on, potentially down to the level of recording exact unit movements which would let us replay turns with total confidence if the DP encounters a crash to desktop at the end of a long turn. We can allow use of future developments from the Python mod community, as long as we trust our citizens to not load mods which reveal the wrong information.
There is the "know your rules" mod to the sid's tips file -- that would be disallowed with no-cheat. What else might we be able to do for roleplay?
We already have to trust the citizens to not play ahead, and we have to trust the DPs to not reload to change game outcomes. Let's trust ourselves to use tools which don't result in cheating, and trust ourselves to avoid things which do promote it.