Thesis: cheating in singleplayer is fine and morally acceptable.
Justification: in my opinion, cheating in singleplayer is fine. If it does not ruin anyone other's game, then why punish it?
Every single M&B Warband engine mod boils down to exactly the same: gathering a party and capturing the world map. There are plenty of mods out there and if one wanted to complete them all, they would not have enough time in their entire lifetime. Cheating to speed up the process is fine, as the lion's share of the gameplay across various modifications is repetitive, similar and plainly dull. Without cheating or modifying the source of OSP/ LSP mods in singleplayer, I would not have been able to complete many of them. Time is money, you know. Why waste it?
Of course there are plenty of unique mods that add more than just weapons, a new world map, armors, NPCs and textures, but they are in minority.
Think of a cancelled mod 'Crusaders Way to Expiation'. It has innovative shaders, scripts, presentations and even a custom launcher. For such labor of love mods like it, Sands of Faith, PoP, TLD, Deeds of Arms and Chivalry, Light and Darkness and many more which I have not played yet, playing without cheats is alright as there are plenty of other elements of the game to dive into. For the majority, however, speeding up the playthrough through cheating is alright as there is nothing else to dive into. The rest of the mods is just a reskin without bringing anything new to the table.
Conclusion: cheating in singleplayer is fine as it saves time; it also is morally right since it does not ruin others' fun.