This is more my imagining a book plot than any real insight, but...

This wouldn't be Apple's first rodeo with Intel. They know how prior partnerships soured. Could a sufficiently powerful shareholder, like the US government, help mitigate Apple's concerns about the outcome of a new partnership? I.e. that Intel would be pressured to honor certain strategic obligations, even if the leadership at Intel isn't so keen?

How can the USG improve the competitiveness of INTC's process nodes with political pressure?

Was the concern in the past that Intel wasn't honoring strategic obligations or was it that Apple realized their tech sucked and TSMC was the only viable path to deliver world-leading products?