My only real guess is that people kept pestering him to fix issues and bugs, and that he basically grew so sick of being someone else's tech support, he just put measures in an attempt to discourage people from even using cheats in the first place. This theory is certainly lent credence by the fact that, he has put in flags in the save files to see if the save is modded. Whether or not said technical errors were related to the mod is probably entirely unrelated but it doesn't take an easy guess to see he probably guessed half of the time it was because they were cheating. I don't exactly condone or support his methods but it would make logical sense as to why he probably doesn't want them.
Well, you can always just say in your patreon and discord you are not going to fix broken saves like Drifty or many other devs say and after that is up to people if they want to risk fucking up their saves but I think going against cheating this hard doesn't look good on any dev, not even DPC.
and dpc motives for no cheating is because he wants people to play his games the way he did makes them instead of with mods that will in a way make it easier on the player.
From that perspective is good but it can also be annoying if you consider that in a way since you want to "force" people to play it your way instead of their way.
In a way is like having drm in a game because many people pirate them, they will always find a way to pirate them and the more they force it the more probably is those people won't support them since no one likes to be forced into things. Kinda why some games in gog with no drm like witcher beat the sales of those with drm shit.
in any case, with the console is kinda easy to turn off those variables.