Larry, why would they want a coke can sized bomb on board? (If anyone knew, I figured it would be you)

It seems like the risk would not be worth the purpose.

I am refurring to;

>>The capsule is filled with muck and smells of the sea. Hugh feels around the floor of the capsule's main compartment, where astronaut Virgil "Gus" Grissom last sat for a 16-minute ride in space. Hugh's left hand closes around a can and he knows he's found the bomb. "Buddy, guess what? I found it," he calls out to his partner. They clean it off, scrape off corrosion and call over the photographers and film-makers documenting the Liberty Bell 7 recovery. Hugh and Buddy don't try to discern why the bomb, which was designed to detonate in case the capsule sank, never worked. Buddy heaves it overboard. <<