Here's another happy looking person
There's a distinct difference between the two and the type of reaction someone would have towards that happiness.
Same can be said for aggression. Aggression is not some on/off switch, it is not a binary thing where it's either 0 or 1, there's degree's and levels.
There was nothing in the Romney / Obama debate that was anywhere close to Romney going "That's a bunch of stuff!". I'd challenge you to find even half as many instances of Romney simply laughing over what Obama was stating. I'd implore you, count the number of times Biden rolled his eyes or rolled his head back in condenscending mock frustration and then count the number of times Romney did similar. Even count the amount of times Romney talked over and interrupted Obama comparitive to the Biden one.
Yes, Romney was aggressive in his debate style. However, to suggest it is similar in aggression to what Biden did is like saying that an air soft bullet is comparable to a .44 magnum in terms of their damaging power. Whether or not that's problematic on the point of Biden is a matter of opinion and will be something to see as polls come out. But to suggest that there is some inconsistency in people liking the way Romney was aggressive but disliking the way Biden was is patentedly ridiculous.