I think you may be misunderstanding the JNJ standstill with Elan. Normally standstills prevent a company from buying another out without prompting or permission (i.e. prevents them from going hostile). But if another company was to make a hostile offer I would bet that this standstill is null and void. Another question I have for BIIB and Elan is regarding the Change of Control (COC) clause for Tysabri. I wouldn't be surpirsed if the COC and Standstill are linked such that if Biogen makes a hostile offer then the Tysabri COC is no longer valid and another bidder could take out Elan and own Elan's half of Tysabri. This could be a very interesting scenario that may actually prevent Biogen from being able to take out Elan easily.

Real value for Biogen would be to make a hostile offer for Elan and then agree to sell the Alzheimer's assets to JNJ.