His intent was not to start supporting you on Patreon, just so that he could get a glimpse of features... He actually used your tool but decided it lacked some features but also provided a lot of what he needed, which is why he made his own version of it.
I will however agree, that the UI as well as the time of release is/was very... "unfortunate", but, I'm pretty sure this was more a lack of care than evil intent.
But at the same time, it is possible to argue that you copied the 3D exporting feature from him. And some of the models you created look a whole lot like the models he created.