What exactly are you objecting to? Since you say “I’m fine with the idea that licensing Docker and Docker Desktop is a good thing to do” it’s not the change, so what is it? The 30 days, them saying they would sue after that, or the tone?
I haven’t seen the messages so I cannot comment on that, but if you accept that the licensing can be changed, whats wrong with writing offenders to remind them to either stop using the product or start paying? And what’s wrong with giving them 30 days, since, in my memory, they announced the licensing change months in advance?