I get the concept.
The problem is Bernie is Bernie and his cease-fire is temporary. It will evolve into a cease-fire because he believes:
He obviously believes that there must be a way to avoid civilian casualties without stopping the fighting, or else he'd be calling for a ceasefire. Knowing the little I know of Bernie, if he had an idea of how to do that, even a stupid idea, he'd say it. He didn't, which means that this "save the civilians" stance is purely ideological and not practical, and he currently believes the reality outweighs the ideology.