Well, the site wrote it with an ampersand (&), which is originally a creative combination of "e" and "t". My nitpick is: shouldn't it be "Et vos, Procter & Gamble?"
Nice one. Never knew this either. Small clarification/update.
The ampersand symbol is in the process of becoming something other than a ligature, specifically:
> The ampersand comes in many different forms. Because of its ubiquity, it is generally no longer considered a ligature, but a logogram.
Unless the Romans did it, but I was under the impression that "organizations" like the Senate (senatus) were singular.
British English tends to refer to organizations as plurals instead of singular.
Also, I'm not sure what the usage would be in classical Latin, but using the singular to talk about a company in French seems perfectly appropriate. IIRC it's the Brits who like to use the plural for companies and institutions.
I've never been clear on that.