Breaking other people's project is definitely malice - it also hurts people who were using this open source package for non-commercial use.
There is a better solution. Unfortunately, it is one that is rather boring for developers: licensing - every author can define the licensing terms of their software, so you can use a GPL3 that requires users of your library to open-source their work based on your library and at the same time support a commercial license without this requirement.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
Breaking other people's project is definitely malice - it also hurts people who were using this open source package for non-commercial use.
There is a better solution. Unfortunately, it is one that is rather boring for developers: licensing - every author can define the licensing terms of their software, so you can use a GPL3 that requires users of your library to open-source their work based on your library and at the same time support a commercial license without this requirement.