A Guy Called Tyketto writes:

If it was a vector, that changes the whole story.

It was indeed a vector from the beginning, so the story hasn't changed at all.

If it was a
clearance that he wasn't going to be able to accept, then there would
be some questions.

I don't recall any mention of a clearance.

Oh, I agree. ATC would never vector a plane like that, don't
get me wrong. But as the OP had mentioned, if he accepted a routing
that he believed he couldn't fly and the weather was IMC, the question
would have to be asked on why he accepted that routing in the first
place.

Since this was not the hypothetical situation, the way it would be handled is
moot.

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