I write 2 scrips for start and stop kagu and test it from root.
It works. But when device connected kagu doesn't start.

cat /etc/dbus-scripts.d/dbus-scripts-settings
/usr/local/bin/start-kagu * * org.bluez.Adapter RemoteDeviceConnected 00:0D:3C:A6:CC:13
/usr/local/bin/stop-kagu * * org.bluez.Adapter RemoteDeviceConnected 00:0D:3C:A6:CC:13

dbus-scripts --debug --system
Parsing conf file /etc/dbus-scripts.d/....
Parsing conf file /etc/dbus-scripts.d/.....
Parsing conf file /etc/dbus-scripts.d/dbus-scripts-settings...
Parsing conf file /etc/dbus-scripts.d/dbus-scripts-example...
Script file /usr/local/bin/start-kagu: arg 1 = *, arg 2 = *, arg 3 = org.bluez.Adapter, arg 4 = RemoteDeviceConnected, arg 5 = 00:0D:3C:A6:CC:13,
Script file /usr/local/bin/stop-kagu: arg 1 = *, arg 2 = *, arg 3 = org.bluez.Adapter, arg 4 = RemoteDeviceConnected, arg 5 = 00:0D:3C:A6:CC:13,
=================================
Arg 1: org.freedesktop.DBus
Arg 2: :1.351
Arg 3: org.freedesktop.DBus
Arg 4: NameAcquired
Arg 5: :1.351
=================================
Arg 1: :1.49
Arg 2: null
Arg 3: org.kernel.kevent
Arg 4: add
=================================
Arg 1: :1.32
Arg 2: null
Arg 3: org.bluez.Adapter
Arg 4: RemoteDeviceConnected
Arg 5: 00:0D:3C:A6:CC:13
Script /usr/local/bin/start-kagu matches
Script /usr/local/bin/stop-kagu matches
=================================
Arg 1: :1.33
Arg 2: null
Arg 3: com.nokia.btcond.signal
Arg 4: connection_status
Arg 5: 00:0D:3C:A6:CC:13
Arg 6: connected
=================================
Arg 1: :1.32
Arg 2: null
Arg 3: org.bluez.Adapter
Arg 4: RemoteNameUpdated
Arg 5: 00:0D:3C:A6:CC:13
Arg 6: Nokia BH-501
=================================
Arg 1: :1.33
Arg 2: null
Arg 3: com.nokia.btcond.signal
Arg 4: link_key_ok
Arg 5: 00:0D:3C:A6:CC:13
=================================
Arg 1: :1.34
Arg 2: null
Arg 3: org.bluez.audio.Headset
Arg 4: Connected
=================================
Arg 1: :1.11
Arg 2: null
Arg 3: org.freedesktop.DBus.Properties
Arg 4: Notify
Arg 5: com.nokia.bluez_headset_proxy
Arg 6: State
Arg 7: Connected
=================================
Arg 1: :1.49
Arg 2: null
Arg 3: org.kernel.kevent
Arg 4: add
=================================
Arg 1: :1.34
Arg 2: null
Arg 3: org.bluez.audio.Headset
Arg 4: Playing
=================================
Arg 1: :1.11
Arg 2: null
Arg 3: org.freedesktop.DBus.Properties
Arg 4: Notify
Arg 5: com.nokia.bluez_headset_proxy
Arg 6: State
Arg 7: Playing
=================================
Arg 1: :1.34
Arg 2: null
Arg 3: org.bluez.audio.Control
Arg 4: Connected
=================================