I am not sure what is meant by "islands which are disabled in "Early Explorers" - does this mean that you can't land on the island at all. ?
Yes, that is exactly right.
I would have thought that you would still be able to land at any of the shores/beaches on any island that was not colonized at the time ( after all the island still existed) - just that you could not access any Port or Town/settlement.
So you should be able to walk through an uncolonized island - just that the reload from the jungle section to the section with the town/settlement entrance would be disabled, creating a dead end.
And just because an island was officially uncolonized - does not mean there is no one there - there could still be a small native settlement of a few surviving Caribs ( especially in the early explorers period.
If you allow the shore, but not the town, then where do you draw the line?
Disabling the town gates will be very odd as you are already standing in front of those gates.
So disable the reload TO the "outskirts"? But even then, you'd have a reload that leads nowhere. That'd be quite ugly too.
The best solution would be to replace the town with an equal-size set of shores and jungles if necessary.
That would mean making two sets of shore locations for those islands that are disabled in Early Explorers.
Possibly with some indian settlements on them instead.
I'd definitely prefer it if that could be done, but it would require a lot of work.
And I'm not sure if that is worth it; if there aren't any towns on the islands, there isn't much to do there.
Plus how many people are going to play in Early Explorers? So I'm not sure it is worth the effort.
So ideally, yes to all. But for practical reasons, we have a simple method of disabling islands for now.