Nod to nationalism, why not?
Because it isn't relevant.
But I do have more than a passing aquaintance with Arran, and also with Mull, Iona and, to a lesser extent, Islay, and know somewhat of the special needs of these communities. Since its' reconvention in 1999, the Scots Parliament (both Labour and SNP administrations) has introduced new land lawssecuring thue rights of islanders and crofters - even allowing communities to buy the land from absentee landlords; it has also, mainly due to SNP and Lib/Dem representation from the northern and Western Isles, tried, with the limited powers at its' disposal, to encourage immigrants to the more remote islands - this policy has ben continued regardless of the administration in power.
I also have a passing acquaintance with those island too (except Islay) - what is your point.
The notion that inherently a new nation state would de facto be better positioned to support the needs of rural communities is nonsense.
As you have inferred the political pressure here (as always) is about the importance of rural voters to political parties looking to win power. And I struggle to see how that is any different in Scotland alone, than in the whole of the UK. Sure the population of the latter is skewed toward those who don't live in rural communities, but so is the former - indeed I think there is a greater dominance of the central belt in Scotland in population terms than there is of any single ares in the UK.
In fact the proportion of the population of Scotland living in rural areas (and their power as an electorate) is slightly lower than in England.
Moreover there is a far greater concentration of population in the central belt in Scotland (over 65% of the Scottish population live there) than there is in London and the South East in the Uk or even England, representing less than a quarter of the population.