I think it's important to note the top demand of the letter (in italics):

"As a starting point, we are putting forth the following categories of action items, the specifics of which we would like to discuss in person with the executive team within a month:

Publicly address and condemn Elon’s harmful Twitter behavior. SpaceX must swiftly and explicitly separate itself from Elon’s personal brand."

I don't know why anyone would think that that would go over well.