The project appears to be based on XeTeX, which is covered by the MIT license. I don't know the full history of XeTeX, but if it was indeed a re-write of TeX/L

The project appears to be based on XeTeX, which is covered by the MIT license. I don't know the full history of XeTeX, but if it was indeed a re-write of TeX/LaTeX from the ground up (and not based on the TeX source code), then the original TeX/LaTeX license wouldn't necessarily apply. But if it borrowed actual source code, templates, etc., from other projects under different licenses, then it probably gets more complicated.