Sure you can use a grommet, any thing is better than nothing.
Using a rubber grommet you'd still need to feed the wire through it, same as with the box connector. It's a real pain when you forget to do that.do they make a rubber grommet i don't have to take the thing apart to install?
Depends on how sharp that hole is. Silicone is not the most cut resistant but better than nothing.Sure you can use a grommet, any thing is better than nothing.