What could they have done, precisely?
Ordered their Swiss subsidiary to blow the place up? Would their Swiss subsidiary have been able to do so? Would they have acted, at all -- given that they were governed by Swiss law? And their Romanian employees were subject to the German military.
The simple fact of the matter is that Standard Oil headquarters may have been rendered powerless by events. Any orders they might've issued to their Swiss subsidiary weren't necessarily going to be followed.
When it was too late they, could have divested and removed themselves - but hanging in there and continuing the business connections was treasonous.