Technically and legally it is an assault, per some lawyer who weighed in on the matter. So if we begin making these people answer for their actions, I’m good with that. It’s a start.
I am a lawyer. Technically, it's battery, which is unwanted physical contact. Assault is the threat of unwanted physical contact. Usually, assault and battery go together. I agree that it's totally appropriate to charge someone with assault and battery if they intentionally throw a drink on you. People need to learn that there are adverse consequences to bad behavior.