The point is PTSD is an issue and suicide is a possible byproduct. It can't be ruled out. I think when you put on a police uniform you are always on duty. If an officer on vacation in street clothes chases down a bank robber and is killed, would we say he was not killed in the line of duty. As such suicide by PTSD has to be contemplated as " in line of duty".
Of course it can't be ruled out. The key word you use is
possible, which means possibly yes, possibly no, and you and I don't know for sure either way. Even so it sounds like you have already made up your mind their suicides were definitely caused by PTSD.
Are you also similarly convinced the only officer who arguably
was killed in the line of duty was killed due to blunt force from a fire extinguisher?
When a police officer is on vacation and the bank robber kills the police officer he has been "killed" in the way that everyone understands the word "killed" to work. If my girlfriend breaks up with me and I kill myself, are we going to claim she "killed" me too?
Look, what happened during the riots was bad enough. The Capitol was overrun for the first time since 1812. People were chanting to hang Mike Pence and the mob narrowly missed coming across him in person. There is no need to exaggerate what happened and stretch the meaning of "kill" beyond all common sense.
That said, if you want to agree with Snoopy that officers who committed suicide after the fact were "
killed in the line of duty" knock yourself out, but you are just inviting the space laser / "antifa did it" people to call you out on your ridiculously strained argument...