If anything, the involvement of Jack Ruby is indictive of no conspiracy.
Indicative of no conspiracy? No it isn't. That's silly.
for the DPD to kill Oswald
the DPD still didn't kill Oswald given this golden opportunity
This idea that the Dallas Police operated as some kind of Borg Collective doesn't fly.
Most cops just do like they're told. Most genuinely thought that Oswald was the shooter.
It's absurd to believe they somehow recruited a loose cannon like Ruby and then trusted him to remain silent for the rest of his live in prison.
Ruby didn't live very long. Joe Valachi lasted a lot longer.