There are plenty of reasons for an orthodox Catholic to decide not to vote for Rudy Giuliani for president, but a claim that he is excommunicated isn’t one them, since he’s not excommunicated.
Perhaps the most misused description of Catholic lore in the mainstream media is the idea that dissenting Catholics are automatically excommunicated. (The next most misused is the idea that the Immaculate Conception refers to the Jesus’ conception in Mary’s womb at the Annunciation.)
Ed Peters points to another example of this phenomenon. In an op-ed for the New York Daily News, Ken Wolfe of the The Remnant, a Traditionalist newspaper, claims that Giuliani is excommunicated because he is divorced and civilly remarried, conflating the state of being barred from Holy Communion with excommunication.