Is this a relevant argument (either way) here? 

While I appreciate considering the applicability of the argument to existing code is generally a good thing, I'm not sure that it makes sense for cases like this where a logical outcome seems to be missing. If you can try/finally and then implicitly pass both the generic except and else clauses, and you can try/except/finally and then implicitly pass the else clause, why shouldn't the construction be logically consistent to cover the other option that is try/else/finally and then implicitly pass the generic except clause?

And, for what it's worth, finding current scenarios for something like this seems heavily biased by the fact that such a construction doesn't currently exist and so code will be written to explicitly avoid it... Or just ignore being necessarily precise, as is often the case with implementations of try/except that I've seen (see the prior discussion between MRAB and Celelibi about overinclusion in the try block).

I'll ask the same question as OP: "Is there a reason why else without except has to be invalid syntax?"