If people are taking the SPC's word as truth because they have priors that cops are truthful, that's an invalid prior based on how much general lying recent events have demonstrated cops do.
If people are taking SPC's word as truth because they have no priors, that's bias to authority and people should probably employ more skepticism.
Do we have any evidence that the Seattle police chief is generally truthful?
Chief Best has made multiple false statements of fact just this week, so, no.