Well, if you were following along, they mention that the market has not remembered those transgressions, which heavily implies the stock price before this incident will be reached again. The stock will hit a local minima, and then bounce back (the symptom of the market "forgetting").
Yep. See also INTC, who got hit down to 44 for that little thing that affected most of their products. They're back to 50 today. The gap between those two might be the temporary social fear factor, that vanishes in a few weeks.
> On what do you base your valuation exactly
Is it even possible to come up with an answer for this?
When somebody claims that a stock is a "bargain" it's not unreasonable to expect to base that on something more concrete than just a gut feeling.