It's pretty routine. As a rule, I almost always charge the highest or most serious charge I can, as well as often charging as many charges as I think I reasonably can. I know that the prosecutor will probably deal, if they can. So I want to give them as much to work with as I can.
I'm not talking about stacking charges purely to stack them, or looking at the facts to get the most serious charge I possibly can. The charges have to be reasonable and make sense, based on the totality of the circumstances. In other words, I'm not going to push for charging someone with attempted murder just because they said "I'm gonna kill you" and pushed someone. Now... if they pushed them off a multi-story parking garage, or in front of an oncoming semi... different situation.
The charges are a tool. In this case, there's room for a murder charge; the officer did intend to use force of some level, and clearly reached for something. I believe and hope he intended to use a Taser... which is why manslaughter or negligent homicide is probably an appropriate place to end up, unfortunately. Meanwhile -- you can be sure he'll be sued for wrongful death to the tune of several million, at least.