Yeah, getting hit by a can of beans might smart a bit. But it sounds like a Saturday Night Live skit for people to actually be recommending this as a valid self defense move, and expecting others to take them seriously. ....
It's a desparation move to be sure, but you're probably hosed at that point anyway. A couple of nice baseball sized rocks would be better, but it beats a suicide charge with a #2 pencil. Kind of like going after a moose with a shovel, or a bear with a zuchini.