The rules are kinda vague on this matter, and in this case a little self-contradictory..
On one hand, it's stated that the PK isn't valid if the Police fire first or escalate the situation to a shootout. On the other hand, it says it's not valid if the Officer escalates the situation to violence.
Those two statements are not the same at all. You could argue that doing bodily harm with a baton constitutes violence. It doesn't help at all how the mention of the tazer says it cannot physically kill or damage the player. If it just said "It cannot physically kill the player" I think the PK would be valid, but since it mentions that damaging the player makes it a prerequisite for invalidating the PK it's safe to assume that a baton serves the same purpose, hence invalidating the PK.
P.S Just fucking RP the arrest, it really is a sight for sore eyes to see people running around frantically trying to dodge the tazers like retards but that's just my opinion.