While a name doesn't mean anything, the group running the ad was called "Latinos for Reform." And, if their goal is to defeat Reid in order to "reform" the current Congress, then not voting for Reid would certainly accomplish what they were after.
Looks to me like they didn't think it through, though. But if a Democratic group ran an ad discouraging senior citizens from voting, I wonder if it would get the same reaction?
Personally, I think any ad discouraging participation in elections is just a bad idea, on the face of it.