It does look similar to the other macOS crashes, except it happens while generating the thumbnails, hence the crash during startup. To change the settings, you’ll have to edit the file that stores them.
Locate the options file on your computer. This page in the user manual will help you find it: File Paths - RawPedia. Once you have it, open it with a text editor. Find the line with RgbDenoiseThreadLimit in it and change the number to 2. Save and close, then try opening RawTherapee again.