Gaslighting in its original sense is a continued process of abuse that leads to a person doubting their own perception, typically with a long term PTSD as consequence. What we are discussing here are possible strategies to get somebody to change their behavior. If you consider people stating a different opinion than you to be gaslighting you, you might want to dig deeper.
I think what is happening here is a difference in understanding of what we mean by empathy, and what it entails in terms of visible action or response. I tried to make it clear that to me, you can both be understanding of the feelings and the (ir)rationality of an abuser and be clear in your boundary-setting (and possible application of protective force) at the same time. The understanding of your “opponent” can help guide your interaction, whether it is verbal communication or other. It doesn’t mean “to be nice” in your response, or accepting their actions.
The reason why I advocate for “more empathy” is because I firmly believe it can make you more successful in clear boundary setting and in communicating and achieving your goals, not weaker, especially in situations where you strongly disagree with somebody else’s actions.
To come back to the case at hand: We seem to agree that the goal is to get him to stop and take the project down. The strategies employed so far to tell him No didn’t make him stop. Now what? I suggested to try a little empathy in the response, something along the lines of “Thank you for offering your help in making NP++ even more successful! We appreciate your effort. For now, can you please take it down, and then we can discuss how you can bring your strengths and abilities to the project in a way that causes less controversy in our happy little community? Looking forward to hearing about your ideas!”. (Only works if sufficiently true; adjust where necessary.)
The goal remains the same. Only the strategy is different. It doesn’t matter if I “like” the person or not, or if I “care” about them. I am interested in achieving my goals, and it requires their cooperation for that —- unless I want to sue. Which I don’t.
With your hypothetical domestic violence abuser, you can shout No all you want at some people and they just won’t stop. If your goal is to get them to stop, you CAN try different strategies. Empathy expands your range of possible actions; it doesn’t limit them.