Oracle Thinktank both punishes stealing (by tagging) and can negate stealing (by shuffling itself back).
Note that the Corp can only steal it right back on their next turn if: the Runner doesn't untag (unlike 15 Minutes), didn't already have 6 agenda points (unlike Quantum Predictive Model), et cetera.
Note also that you don't have to cash the tag in for the -1 agenda point (you can just keep it around for some tag-gates, or spend it on another tag-cost).
PS. A “purple Oracle Thinktank” (Haas Thinktank?) could do a core damage to be stolen and heal a core damage to unsteal itself:
As an additional cost to steal this agenda, the Runner must suffer 1 core damage.
[click], remove 1 core damage token: Shuffle this agenda into R&D. The Corp can use this ability only if this agenda is in the Runner's score area.
The Haas Thinktank is an interesting concept, but would already be better than this by virtue of the fact that core damage (whether removed or not) would still have lost the Runner one card. To my knowledge, there has also never in the entire history of the game been an effect that removed core damage. To add one in would feel odd, at least to me, as it would remove the sense of permanency that receiving it instills. Lastly, it thematically doesn't quite add up. A corp could bury their own lead (remove a tag) or sharpen their public image (bad pub) but... how do they forcibly repair the anatomy of the runner?— Chezni
Also, I think it should be kept in mind while Runners are perfectly capable of removing tags, thus allowing them to defend against Oracle Thinktank retrieval, the lack of core damage removal means that this hypothetical Haas Thinktank agenda is effectively always retrievable for the corp except as the seventh point for the Runner.— P. T. d. l. R.
core damage is partially removable by permanent maximum hand size increases (which prevents automatic flatlining, though wouldn't prevent Ontological Dependence from being fast advanceable).— D4v1d-Gr43b3r
but, I agree with your criticism, that core damage as a Corp-resource is different from tags as a Corp-resource, because it can't be automatically removed like tags can (without any cards just the builtin game rules, and obviously four tags can be removed in the same turn if it's necessary and affordable).— D4v1d-Gr43b3r