Then don’t make a whole big public announcement about it. As someone from the outside this just reads like a post specifically to generate drama and attention but not giving details as to direct it at anyone in particular.
I don't understand. How do you resign from a public project without resigning from that public project? If it is not about the resignation but about the message, do you think that a "we are resigning as a whole team that was made pbulic and we do not provide any public reason for that" would work any better?
It's not like there's some membership card with paid dues. Their responsibility was to anyone that viewed themselves as part of the Rust community, and consumes anything to do with that community (whether or not they put anything into it).
Not informing all the people of that community because it appeases random public commenters would be a far worse failure of their duties than letting the general public gossip.
They did have the option of finding replacements before leaving.