I think that was a tough call to make. With only three fast bowlers selected, if you were to play Permaul then Dowrich probably doesn't get selected, weakening the batting. I would imagine the hope is that Samuels can be as effective as he was against Zimbabwe, especially bowling on this wicket in the fourth innings.
I believe Shiv should've been given the opportunity to say farewell, much like the Indians did the same for Tendulkar. But it is more than just sentiment. It would make more sense to use the experience of Shiv against a strong Aussie attack than to throw five youngsters who have less than 10 Test matches each against them, only for these youngsters to get demoralised by poor results. These youngsters should be blooded against weaker teams like Zimbabwe and Bangladesh, to build up their confidence. What's the point of giving a Test to Shai Hope, who's only had 15 FC matches? These youngsters have FC averages in the 20s and 30s...what about these stats say that they are natural successors to Shiv? And by treating Shiv this poorly, what message does that send to the youngsters now playing for the West Indies? It says that it will be better to look after yourself and do what Gayle did, because the WICB will shaft you in the long run.