Jumping into the future a bit, but I was just looking at Tithonium again, and I’m not sure if the ‘cannot host cards’ clause actually prevents it being Oversight-ed.
I know the ins and outs of the Thrones rules better than Netrunner, and based on those I would rule that Oversight successfully rezzes Tithonium, but then cannot resolve its second effect of hosting on Tithonium due to the now active text, and goes to Archives like any other operation when it finishes resolving. I had a little look in the ANR FAQ and there are a couple sections that support this interpretation (although for different reasons than in Thrones). From FAQ 3.1.2:
Triggering Actions and Abilities
A player can only trigger an action or ability if its effect has the
potential to change the game state. This potential is assessed
without taking into account the consequences of paying play,
install, or rez costs or triggering any further abilities.
Cards that use the word “cannot” prohibit an effect from
resolving or an action from taking place. If two cards conflict,
and the first card prohibits an effect, ability, or action using the
word “cannot”, the second card cannot be played or triggered,
unless the prohibited action is a condition granted by way of
a non-prohibited effect. It should be noted, that while that
card could then be played, the prohibited part of the effect still
An inactive card retains its printed characteristics (name, card
type, faction, cost, subtypes, influence, etc).
So the question is, does that ‘etc’ in the Inactive Cards section include card text? I don’t think it can do, based on the current way certain cards are played - it is certainly possible, for example, to trash an unrezzed Architect. This means that Tithonium can host cards, such as Caissa programs, while it is unrezzed, although they will be trashed if it is rezzed.
It also means that, at the time of playing Oversight, when the assessment of potential described in the Triggering Actions and Abilities section takes place, an Oversight targeting an unrezzed Tithonium certainly has the potential to fully resolve and change the game state, and can therefore be legally played. Once the resolution has started and Tithonium is rezzed, I think the second part of the effect would come under the category of ‘a condition granted by way of a non-prohibited effect’ which is then itself prohibited, resulting in the free rez outcome I described above.
I’m sure the devs could easily rule this out in an UFAQ on the grounds that ‘we didn’t mean it work that way’, as they so often do, but I thought I’d bring it up anyway. If I’m right in my interpretation, and it turns out that the devs are fine with this and the clause was actually just there to make Tithonium immune to Parasite/Egret/other runner cards, then we have one hell of a piece of ICE on our hands