You missed the part about not having cheats in the version of the mod intended for speedrunning.

The only people who are going to be able to run 1.5 are those who back it up now. I've talked to lupo and he's adding a modular system to his mod. You download the base without any of the scripts affecting the game and then copy a bunch of .zip files containing a single feature each. It's gonna be possible to make an "official" speedrun mod with that. Whether or not it should be mandatory or not can be decided later. Maybe add separate versions to the version list with and without mods? Like 1.6.0 and 1.6.0 (modded). Also talked to Grimalackt and I think he's okay with transfering his additions to the new set up when it's done. It wouldn't be so big of a deal to me if they didn't remove the walldodging. Solo speedruns without it seem extremely boring to me.

I can make a custom build of the modkit that doesn't include any of the cheats.

This game has a ton of uncontrollable rng, and on top of that you get speed potions + dupe on consume trinket. With that, whoever can drink more times in a row gets the best time. No skill involved beyond being able to do the route no matter how slowly. So my suggestion is to ban speed potions when the new patch comes out. This can very easily be done with a mod (the same I've talked about in a different thread).

What about mods? IAmLupo's mod has a script that brings back wall-jumping to 1.6, as well as other useful things for speedruns like bot killing script for botless runs. I could ask him for permission to make a version of the mod that only includes scripts for speedruns.