Non-lethal weapons would allow protestors to protest without getting killed.
Protestors should be able to protest WITHOUT the police using either lethal or non-lethal weapons against them.
The important thing here is to take away the governments ability to kill.
Except that you are not doing that.
You are providing the police with pain-compliance (aka "torture") devices.
And as can be seen in many news reports, once the police/government has them, they will use them. And that use will not be INSTEAD of more lethal options. They will be used when the victims do not IMMEDIATELY follow the orders of the police. Even if those orders are illegal to begin with.
Those weapons will be treated as a "force multiplier". Not as a preferred option over lethal force.