Unless this would somehow break the game, I find it very odd that you can't save (from what I've heard, I haven't actually tried it myself) or earn achievements if any cheats are being used, even the ones that don't help you. I know Steam doesn't have any sort of policy on it, since in games like Skyrim you can earn achievements when using console commands. And since I imagine mods still allow you to save and earn achievements, it really just seems like an arbitrary limitation to me.