mrstfs, IMO, the person LE had in mind when they asked that the arrest warrant remain sealed b/c "they were concerned about the safety of potential witnesses" might very well be KK's BFF. IMO, she's probably the one who's been chattering like a magpie to LE ever since the R's contacted them.
Since PF was in custody at the time, the logical question becomes: If KK's BFF is the one LE meant when they talked about witness safety, who did/does LE think poses a physical threat to KK's BFF?
<modsnip: rude> JMO.