Nail clippers are not allowed now!? I fly with nail clippers all the time (including to/from the US) and have never had an issue. Looking at the TSA site, nail clippers are explicitly permitted as well [1]. Was the agent actively looking to hassle you?
[1] https://www.tsa.gov/travel/security-screening/whatcanibring/...
[0] https://www.alamy.com/stock-photo-chromium-scissors-scissor-...
Both are complicit in far worse IMHO.
From a certain point of view, it's better for the TSA agent to be soiled with vomit than it is to allow a potentially contagious passenger on what may be a very long flight.
It's the little things. As he stated, the agent wouldn't let him sit down and it was over a pair of nail clippers. Perhaps the vomit wouldn't have made them blink at all, doesn't mean I wouldn't get some form of enjoyment out of it. Sounds like the agent was being a prick. Are we surprised?
There's a fair discussion about "was the way you confronted them that of a professional adult" but at the end of the day, I'm finding it hard to honestly be too upset at the language used outside of a very token "tsk tsk". TSA has not had a history of treating my wife and I respectfully so it's difficult to reciprocate, and can even see the argument that by adding social friction to working there you erode their ability to push policies like this if workers go "wait this may be a bad idea that may make people really angry at us." ESPECIALLY now that there's no real legal recourse outside of petitioning congress.
(An anecdote: I was very sick going through security recently, extremely sleep deprived and falling over without support, they pulled us over to secondary screening and refused to let me sit down while they were checking my bags, ended up vomiting into a trashcan while the agent gave me lip. Turns out all this was over a pair of nail clippers the wife forgot she had packed... and on the RETURN trip.)