The devkit is a modified version of the Unreal Engine 4 which runs in Windows through the Epic Store.
It is not a standalone program which FUncom has the complete and sole right to do whatever they want, nor it is a program that works by itself.
To run a program that is designed to run in Windows in Linux is one thing, but to run the development environment in which it is made if it is designed to run in Windows in Linux is another.
Not saying it is impossible, but it would not be “running the devkit in linux”, they would need to make a whole devkit to run in linux, and that would need to include a Unreal Engine base that run in Linux as well.
That being said, you can “theoretically” use the Unreal Engine from Linux to run the devkit source if you know how to compile C and get the GIT of its source and recompile all the stuff, effectively “making your own” devkit in Linux.
That requires you to know what you are doing.
And probably the one reason the guys do not “make that themselves”, as they would need to support it, and using it in Linux is not a walk in the park. I know that because I do use it in Linux.