Re: An alternative solution
I think it's interesting in respect of potential motivation, but it clearly could not affect the outcome, as you say.
As it happens, I live in a part of the UK that also benefited very significantly from EU investment and also voted to leave. We don't have significant numbers of 'incomers', but we do have a very significant exodus of the young and educated to other parts of the country, so you could postulate a reverse effect. Correlation, though, as we all know, is not causation.
I wouldn't make too much of their "because it is still their home" argument: tell that to the EU citizens living in Britain and British citizens living in the EU that weren't offered a vote: that could genuinely have made a big difference to the outcome.