While I wholeheartedly agree that the employer cannot keep you from drawing unemployment if they fire you without a good misconduct reason, I also agree that you need to be looking for another job ASAP. Because it is obvious you are working for a rude jerk. If you quit, you might even have a chance to receive unemployment insurance, because they might look at the circumstances that forced you to quit (especially if you quit immediately after one of these real ugly verbal assaults) as a valid, job related reason to quit. They'd of course, look into whether you had exhausted every reasonable alternative before quitting.
Have you told your employer that you do not like for him to speak to you that way, or that you find his language offensive? Above all, never get so outraged and emotionally caught up that you fuss back, cuss back, or argue with him about what is happening on the job, or unemployment or anything else. That might actually go into "insubordination." Regardless of how provoked you are, it's never appropriate to yell at your boss. Of course if he responds to your professional and quiet reasonable request by screaming and threatening your job, then you just say, "Well, I'm doing my best here. You need to do whatever you feel you need to do."
The threats are likely just that, threats. That is his management style, and it's not likely to change. Neither is he likely to scream, "You're fired!" on the spot, but if he does, walk away on his order and go home. If he escalates to the point you feel threatened physically (and some bosses have gotten so carried away they have actually thrown something at or attacked their employee) this is the time to walk off the job and quit IMMEDIATELY. You may think of calling law enforcement immediately and pressing charges if it got really violent.
But I agree with chyvan, anyone who would threaten this way is probably much too stupid to make this sort of thing stick in unemployment, where, in order to terminate an employee and keep them from getting unemployment, the employer must demonstrate that they had a valid, work related misconduct reason to terminate. There probably should be prior warnings. The type of insubordination that would get you fired without unemployment would be if you scream, "I won't do it, you !@#$% and you can't make me!!!" and then threw a staple gun at his head.
If he were to make the "insubordination" comment on your separation information, it would simply provoke a lot of questions about what you had done, specifically that was considered insubordinate, and if you had had any prior warnings, and even if he made up things and tried to claim you had done them, they probably wouldn't keep you from drawing unemployment IF he did fire you. Unemployment insurance costs the company money. If they got to decide who gets it and who doesn't, there would be almost no one drawing unemployment, would there? Firing people at random, while not illegal, is not a good business move. Threatening to fire people is a management technique, meant to scare you into submission. If it is effective, then it's good for the company, right? But working for a jerk and a bully is no fun. Be looking for another job while you are still employed there, and get ready to move on seamlessly when you have another position lined up.

