Yeah we most likely need a new trigger action for the update of PB2.
This should help us if they were to add this.
Gun > Call trigger 'A' when gun 'B' is holstered = This trigger action will call trigger whenever the gun is holstered, perfect for this situation as you mentioned above.
Yes I've added that trigger idea to trigger idea thread v4.
viewtopic.php?f=149&t=24982&p=214637#p214637