guy has probably been drinking a lot of phlegm
I worked in a Starbucks in the late 90s, and did not ever spit into anyone’s drink, even though there were hundreds who deserved it.
There were folks who were a-holes and who justified it flippantly by saying it was because they hadn’t got their fix yet. Those folks secretly got decaf.
A coworker gave folks an extra flavor called scrotum sweat when they were uncool. Right there in front of the espresso maker.