It seems a tad unreasonable the amount of aggression that is coming from your camp.
Remember; you are not earning money from XNT.
As somebody who has been in all manner of mod communities before, you have to remember that yes, XNT is your brainchild, but its a brainchild adapted from Goldhawk's own work.
If somebody has taken it upon themselves to modify your own brainchild, and play with the assets a little, perhaps re-work elements, then be honoured by that fact. Somebody has been inspired by you, has seen the work that you have performed and considered it worthy enough to take the baton and run with it.
Isn't that a thing to be proud of?
If you are uncomfortable with that fact; then tact and discernment transcends the domain of anger every time. As a mod developer, part of the role is to behave in an orderly, measured manner when points of aggravation such as this one occur.
Just my two bits.