I'm not sure what you think this line of discussion was about, but having a cop point a gun at you because he thinks you are possibly in the process of committing a felony is not a misuse of police power.
If he beats you up after you are compliant, then we are talking about abuse. Forces you to confess, abuse. Any unnecessary roughness while you are in custody (e.g. The Ride), also abuse. But if he legitimately suspects you are committing a crime and asserts his control to stop it, then he is merely doing exactly what we (society) have paid him to do. It only becomes a problem if he abuses that power after control has already been gained.
>having a cop point a gun at you because he thinks you are possibly in the process of committing a felony is not a misuse of police power
That's hardly something that everyone believes without qualification. I'm not saying you're right or wrong, just that I perceive a social context where it is normal to consider it a potential misuse of power depending on various factors.
For instance, suppose you were stopped and had a gun pointed at you because you resembled someone involved in an armed robbery, but it appeared they had little more to go on than race and gender.
You'd agree it's a fact that some people have perceived a situation like that, as victims, right? And if it was as they perceived, and a pattern, wouldn't it then be correct to consider it an institutional misuse of police power?
One thing to consider is that pointing a gun at a person is not harmless. It carries a risk of inadvertently discharging the weapon. How many times have you heard the admonition to not point a gun without the intention to shoot?
Accidents happen, and sometimes make the news, especially when the officer says they thought they had their taser. Pointing a gun is also a threat that suggests the victim might be shot with impunity. Statistically, there are probably people who have heart attacks or strokes due to the stress. Even if most officers are professional and trustworthy, there's no way to know in such a situation before the outcome.
Having a cop point a gun at you because he thinks you are possibly in the process of committing a felony is reason enough for suspension in many European countries like Germany and Switzerland, for example.
I know that this discussion is about US law, but I want to add this here to put in perspective how skewed law enforcement regulation is in the US.
Much of what's perfectly acceptable in the US would be considered abuse of power in Europe. Such as pointing a gun at someone just because that someone could possibly be in the process of committing a felony.
If he beats you up after you are compliant, then we are talking about abuse. Forces you to confess, abuse. Any unnecessary roughness while you are in custody (e.g. The Ride), also abuse. But if he legitimately suspects you are committing a crime and asserts his control to stop it, then he is merely doing exactly what we (society) have paid him to do. It only becomes a problem if he abuses that power after control has already been gained.