Both are valid, it’s journalistic headline abbreviation. It can be read as:

> [the] shutdown [was] to make sure

Or with your correction it would be read as:

> [it was] shut down to make sure

So it’s not incorrect in the source article, it is just using the noun shutdown, rather than the verb to shut down.

You are being way too generous. Your first expansion is a very big stretch.

Perhaps, though I’m not arguing that it was a good headline. My point was only that it is a valid headline, as long as you understand that shutdown is the noun.