Obviously not, since Lincoln and Buchanan and others believed the actions to be illegal.
Lincoln could have accepted the status quo, and many lives would have been saved.
The same could be said about Sumter.
Buchanan chose not to challenge the Confederacy.
And whether or not Lincoln thought the actions illegal isn't the point, so much as the Confederacy wanted peace, and to be left ALONE. They even fought a defensive war as long as possible to show that fact.