Stupid? Yes. For making the movie in the first place.
Coward? No. They didn’t cancel the theaters did. But one real life attack and they would be in endless lawsuits from smarmy individuals who knew the risks but blame Sony anyway.
It would've been better satire if, like with the classic Mouse That Roared, the humor is directed to a fictional country and leader, perhaps with a lot of similarities to a real one. Not taking the risk? Of course they can't.
What Sony should be doing is taking responsibility for their lousy computer security and low-class gossipy employees. It's not the government's job to secure a corporation's computer systems.