Unfortunately they cannot use any of the Google Maps imagery as they are not partnered with them, so we’ll have to do with what Bing Maps has to offer. I can see two ways to slightly improve this matter, one would be to use as much of the high-detail data as possible with a stricter water mask, like this awful mock-up.
Or they could use the immediately lower detail level to fill in the missing data, but it means that it will not look good compared to the full detail of the rest of the imagery. This could be countered with only some partial blur (as visible in the same spot from the Oceania trailer) to make it transition more smoothly to the high-detail parts of the imagery.
In the end, that’s up to the scenery team doing the water masks to decide. They might feel that putting the same amount of effort in a different area will result in a higher benefit (western France has got some awesome water masking with the latest update). Or, they think they might be onto better imagery for the area soon, which would render the current water masks obsolete, that means it would be a good idea to wait until they have better data to work with.
I do hope these islands, as well as many other parts of the world ruined by cloud artifacts, will look better someday. An Oceania World Update would be great. It will be exciting to see what the Bing Maps team will be able to do in the next decade as the simulator continues to be supported.