With a nuke warhead, close, as with hand grenades, was good enough.
Yup. And for the goals it was supposed to achieve in the mission it was intended to perform, apparently the Shkval does spectacularly well. Its primary initial mission was to kill a Western sub that had fired a wire guided torpedo before the torpedo could hit the Russian sub.
It does have some major drawbacks, which is why it’s not terribly popular on the world arms market. If you fire it, it’s extremely easy to see the launch and locate the sub that launched it, for starters, so basically it’s a one way trip for that sub if there’s surface forces around. It’s also enormous, so a sub or ship can carry fewer shots and has to have the oversized tubes to launch it.