Haven’t read the dissent, but I think it is easy to disagree with how broadly the majority defines official acts and that they precluded examination of the president’s motives. There’s also an issue of how little guidance they gave to decide what is official and unofficial.
Taking Trump’s interactions with Pence, for example (IMO one of the most problematic situations in the whole thing). They don’t explicitly say it’s immune, but it is official.
Seems like their standard for official but not immune is that it is “manifestly or palpably beyond [the president’s] authority.” Trying to get the VP to unilaterally decide the outcome of the election seems unauthorized to me, but they say the court can’t look at whether he was trying to get the VP to do something illegal. Without considering motives, it seems like an impossible burden to meet. I’m not sure what the government could possibly show, besides motive, to establish that it’s not authorized.
They leave open the questions related to people outside the executive branch, but there’s so little guidance given on what to do with it that this will just be back for another round in 4 years, unless Trump wins the election.
Otherwise, he will likely be dead before this case is over.