In Sam's defence the dude holding the cup touched Sam first.
If you're so in somebody's frigging face that he can't hold a cup up to his own mouth when eating and drinking are means of survival, then if you wanna get all technical and shit, you are impeding their means of sustaining life for that five seconds or whatever.
This whole technical thing is as stupid as fuck, but Sam was already going there with the "Hitting" bullshit.
Of course, if I were that dude, I'd have started deep mouth breathing and coughing and shit.
"I threw that spittle away, it doesn't belong to me anymore and what happens to it after it leaves my body isn't my responsibility."
Feh.