This bit's quite damning.
Even the American TV news anchor, Gayle King, a close friend of the Sussexes, agrees with the approach: “That would seem the right tack to take from the Palace, just have no comment,” she said on her morning show last week
Also, it hadn't occurred to be that they were 'blaming' Charles/William, because it was to hurtful to face the fact that it was HMQ who made the choices.
And that would be the only reason for the summit, wouldn't it? To see if they can get a changed decision. But they need it to to be something that they can ascribe to Charles or William changing their mind. Not the late Queen's decision, that is likely to be upheld