This is true. Not making a decision counts just as much as making one - sometimes it is just easier to let things pass.
It is called the trolley problem.
Pulling the lever save five workers, but will kill one man. Not pulling the lever kill five workers alive and will keep that one man alive.
Not making a decision is also a decision.
I totally agree with you. Not making a decision is also a decision. Because doing something and not doing something both will lead to a series of events that we directly had influence over.
Couldn't have said it better!