> One is a 12-month price target for the stock, the other is a takeover price (based on the long term)
If you expect a certain price in the future, then you should want to buy/sell toward a similar price (minus interest) in the present, shouldn't you?
> where GS is acting on behalf of the company and its existing shareholders.
That explains wanting some premium. It doesn't explain the difference between 30 and >54.