WowAce

First,
You may have already known, while at beginning in Cata there was no tracking for Archaeology, a "Track Digsites" was added sometime later.
A minor tuning in Display.lua should make it useful.

Second,
In my opinion the node visibility logic should be:   (I can track) and (I want to track) and (while tracking is useful)
For example for Mining they are (I can Track Mineral) and (I turn on Track Mineral) and (I can mine mineral node),
part1 & part3 are the same thing (Have Mining learned).

For Archaeology they are slightly different, part1 is still to learn the profession; part2 is the "Track Digsites" I mentioned above;
the part 3 (while tracking is useful) can be interpreted as (only shown while I'm in an active digsite, hide otherwise since there's nothing to dig anyway).
There's a simply API CanScanResearchSite() can achieve this (it's used in Blizzard_ArchaeologyProgressBar.lua) .

The problem with CanScanResearchSite() is that there's no event that fires to indicate when you enter or leave a dig site, so the only way to use this function is in an OnUpdate poll, which is generally something you want to avoid doing. An acceptable compromise might be to poll only while in a zone with an active dig site.

I personally put it in Display:UpdateVisibility() and directly replace visible = IsActiveDigSite() with visible = CanScanResearchSite(). So they won't automatically show up until I do something to update the maps, but good enough to me.

Also you can listen to "ARCHAEOLOGY_SURVEY_CAST" like Blizzard_ArchaeologyProgressBar does, this bar appears after first use of Survey.