Often wondered that myself. Possibly because it was seen as a low-population island with plenty of room for an influx, possibly because it was seen as a much safer solution than throwing a lit match into a known powder-keg in the Middle East (boy was that ever a thought considering what we've seen since).Why Madagascar? Odd that the Nazis mentioned it as well.
And you’ve just reminded me that my order for that Jenkins tome never arrived from Amazon.
I'm pretty sure a few swivel eyed rabbis could have been persuaded to discover references to a 'holy island of Judah' or something equally nonsensical to justify it all.
Which is pretty much what happened with the justification for sectioning off a large part of Palestine in any case.
Bear in mind the awful crap we ourselves have seen with some of the more endearingly swivel-eyed among the loyalist community in Northern Ireland, with a few half-hearted attempts to persuade the world that they are the 'lost tribe' of Israel.
Which makes just about as much sense as anything else to do with the efforts to historically contextualise such claims.