Despite the evidence that you think he exists, and he has a vote and he has expressed an opinion? Your idea of an analogy then means that you think your opinion is worthless, You really shouldn't play the relativist position as it shows how ignorant of it you are and indeed how irrelevant it is to the discussion of how jakswan might vote.
I've set out my stall in the OP and have not deviated.
I think the point raised by the OP is very worthwhile and was actually established in 2015 which demonstrated that an electorate that says it is going to vote one way doesn't necessarily.
There is no evidence that Jak is going to vote Labour without Corbyn or can there ever be.
lack of evidence is many atheists reason for being atheist isn't it. Therefore it's a good example. But analogies are not homologies Sane which I think is where your mistake might lie.
Now if Jak expanded then I might shift from a lack of faith in his claim to conviction of it...that's how these things usually work.