Firing a taser at someone threatens them with serious physical harm.
A taser has a limited range. Brooks was running away from the police officers. They should know the range in which it operates, and it stands to reason that the further he runs, the less likely or outright impossible it becomes that they will be in danger from it, in the hands of an untrained operator, as he moves farther and out of range.
They have the whole resources of their dept behind them, they've taken details of his car and his ID, and again, there's no indication Brooks meant any harm to any member of the public, so all they had to do was tail him at a distance
Doesn't even matter if it was serious or not. The case of Rayshard Brooks satisfied BOTH clauses and it only needed to satisfy ONE of the clauses.
It does matter, because the use of force regs specify it. There are four clauses, in the form
1. (Clause 1) and (Clause 2); or
2. (Clause 3) and (Clause 4)
So either para 1 OR para 2 can justify use of force, but if applying one of these paras, then BOTH clauses in the numbered para MUST be satisfied. They are not.
Clause 1 fails because the taser is a temporary incapacitation device, not "likely to cause serious bodily injury"
Clause 2 fails due to lack of indicated intent to use the taser toward others, and by the holder of the taser running AWAY from the officers.
Clause 3 fails due to lack of "serious physical harm", and clause 4 fails because there cannot be a "continuing" threat of something that was lacking in the first place.