Can I use ReFox to somehow get the source code from the distributed EXE (assuming he didn't use ReFox to encrypt it)?
Sure. You should be aware of three limitations, though:
1) Comments won't be recovered unless they are in a VCX/SCX file and the EXE has been created with debug info.
2) Constants in include files cannot be recovered at all. You get an empty include file and everything in the source is replaced.
3) Certain expressions are simplified. Where the original source code read x = 5+3 you get x = 8 when you decompile. With code that calculates positions or lengths this might be less readable.