The SCGI XML-RPC transport used in Flexget looks exactly like the GPLed one that's floating around. An example of this can be seen here or here

This also matches my experience looking for a better licensed SCGI Transport back in start of 2015 (before this code was added to Flexget) which resulted in me writing my own transport as none existed.

I suggest replacing the plagiarized SCGI Transport with my own version as it should have no license issues and be functionally equivalent.