The Black Flash has no quarrel with speedsters playing by the rules, and we doubt many will shed a tear when Eobard Thawne finally gets what’s coming to him.
Only this time, they’re not sending Time Wraiths, but the speedster they corrupted from Hunter Zolomon into this new, Black Flash.
Having injected himself with dangerous drugs to amplify the Speed Force flowing through his cells, Hunter eventually gave himself a new name: Zoom.
If The Flash and Legends of Tomorrow were keeping to the rules of the comics, then the Black Flash (if Hunter has really been given that identity, as it appears) would only be visible to those connected with the Speed Force.