The way I see it, this could end in several ways:

I notice that you left off an outcome that if anything allows you to make your point stronger.

5) Attempt to make an arrest. You see that the suspected criminal has the capacity to use lethal force against you (he is armed) and you suspect that he will use it against you. You shoot the suspect. His use of lethal force against you is never more than counterfactual (ie. a valid suspicion).

For consistency some "6)" may be required in which the first "attempt to use lethal force against you" is successful. I suggest that this action is not necessarily Evil, for similar reasons that you describe for scenario 4. Obviously this is less clear cut and has more scope for failure modes like "black suspect reaches for ID" so we want more caution in this instance and (ought to) grant police officers less discretion.