Alternator output current is self-limiting and will not exceed its spec by much of a margin for long, and hence is very unlikely to damage the battery isolator. A 95A alternator is unlikely even to be able to blow a 100A fuse, which might take hours to react at 130A.
What the fuse might offer is a degree of protection against wiring burnout if the battery or main cables on one side of the isolator become short-circuited, and the battery on the other side dumps a heavy current through it. It's sufficiently unlikely though, that not many installers fit a fuse in that line. Also, the resistance should be kept as low as possible to ensure that the secondary battery receives full charging voltage even when there is load present.
