Completely confused, as this mod worked with every mod I had installed beforehand. I am unsure what I have done wrong.

Here's the log from startup, even though the game crashes entirely before it can.
latest.log

Looks like it‘s connected to SecurityCraft?

Interesting. I wonder why. Again, REID worked just fine with everything I had installed beforehand. So strange that SC is now incompatible, even without changes.
Thanks. I'll test to see if removing SC helps, or maybe downloading a different version of it
Edit: Quick delete of SC made no change. Still crashes at startup

I did some testing on my own (very basic, literally just adding a few mods at a time to see what works and what doesn't) and I did find the incompatibility. It was the mod LootingVI. I removed it and everything loaded perfectly again.