Coroners Office Investigators, UPRR Police, and CC Parks Police as system subscribers and sworn personnel already, certainly should qualify for being trusted with at least some of the encrypted channels.
Also, plenty of mentions on the Admin channel today of the "encrypted Admin" channel -- some personnel attempting to sign-on with Metro Dispatch were told to switch to it, other units were not.
If LVMPD is truly concerned about opsec/comsec (all of a sudden, after deliberately leaving some channels non-secure for a period of time...) and truly competent, they will encrypt Admin, Records, & perhaps some others like CC Animal Control (they're sometimes involved in raids & other sensitive investigations along with the LVMPD Animal Cruelty Unit) but then dedicate a non-secure VHF/700MHz patched LVMPD Metro Dispatch"Access" channel for outside agencies like Mohave County SO et al. There are already numerous cross-patched VHF/800MHz mutual aid channels around, but the VHF sides seem to be forgotten about, and the 800MHz side has restrictions on the type of traffic the channels can be used for.