Broden is requesting the FED's look into possible criminal activity by the local constabulary. He isn't asking the FEDs to prosecute the bikers.
As to which selective-law-enforcement agency is worse, that depends on the case and situation.
I think it would be more appropriate to escalate it to the state: the Attorney General or the Texas Rangers.
Paxton is a straight shooter, as far as I remember. He would get to the bottom of this.
I suspect the betrayal will lie with BATF and DOJ more than local police.