The spitter spat upon a politician with whom he disagreed, lied about having spat, and tried to get into a spat as a result. All apparently without the slightest trace of class, tact, or decorum.
This respondent is replying to the uncouth behaviour and thuggery with a show of force, to intimidate the boorish. If they had restrained their actions, he would have made no such threat.
Full disclosure:
Responding to such people is always a dilemna.
If you mirror their tactics, they will cry "Help! Help! I'm being repressed!"
If you ignore them, they go away smirking, and escalate their tactics.
Proverbs 26:4-5 says:
Do not answer a fool according to his folly, or you will be like him yourself.
Answer a fool according to his folly, or he will be wise in his own eyes.
Apparently, Solomon had to deal with politics too...
OTOH, politics was really hardball in those days.
See 1 Kings 2 for a description of how Solomon's brother tried to connive his way into the kingship, and was killed for his trouble.
I agree. The poster was suggesting to "seek them out". Revenge benefits no one. However, in a crowd of people, pointing out the childishness of an action may work. A statement such as "I don't believe spitting to be an adult form of disagreement" may humiliate. Admittedly, it wouldn't work in a room full of disrespectful partisans. But I do believe that acting with dignity makes the spitter feel frustrated.