A: Luke is isolated because there’s a far bigger threat coming. The tragedy is that he had to focus on that while Snoke took advantage of the vacuum. He knows lives are being lost but EVERYTHING could die without his effort. However, he failed to see the enormity of how far the First Order had spread in his absence, and realizes the new generation needs his guidance and can’t solve everything alone.
That’s an amazing idea. I might actually use it in my sequel edits to remove Luke’s surly attitude, while still explaining his absence. The bigger threat would be revealed to be Palpatine, giving that plot twist more foreshadowing.
Thanks! Go for it.