Testing on a random system with NetworkManager in debug mode; I got just the details I need:

Dec  1 20:10:21 ubuntu ntpdate[5194]: no server suitable for synchronization found
Dec  1 20:10:23 ubuntu NetworkManager[5144]: <debug> [1291234223.200914] [nm-manager.c:1223] user_settings_authorized(): User connections permissions: net 3, con 3
Dec  1 20:10:23 ubuntu kernel: [  408.302212] iwlagn 0000:03:00.0: ACTIVATE a non DRIVER active station id 0 addr 00:22:90:3c:5d:50
Dec  1 20:10:23 ubuntu kernel: [  408.334058] wlan0: deauthenticating from 00:22:90:3c:5d:50 by local choice (reason=3)
Dec  1 20:10:23 ubuntu wpa_supplicant[2087]: CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys
Dec  1 20:10:23 ubuntu avahi-daemon[1716]: Withdrawing address record for 10.153.108.171 on wlan0.
Dec  1 20:10:23 ubuntu avahi-daemon[1716]: Leaving mDNS multicast group on interface wlan0.IPv4 with address 10.153.108.171.
Dec  1 20:10:23 ubuntu avahi-daemon[1716]: Interface wlan0.IPv4 no longer relevant for mDNS.
Dec  1 20:10:23 ubuntu NetworkManager[5144]: <info> Policy set 'Auto eth0' (eth0) as default for IPv4 routing and DNS.
Dec  1 20:10:23 ubuntu NetworkManager[5144]: <info> Policy set 'Auto eth0' (eth0) as default for IPv4 routing and DNS.
Dec  1 20:10:23 ubuntu kernel: [  408.350094] cfg80211: All devices are disconnected, going to restore regulatory settings
Dec  1 20:10:23 ubuntu kernel: [  408.350626] cfg80211: Restoring regulatory settings
Dec  1 20:10:23 ubuntu kernel: [  408.351174] cfg80211: Calling CRDA to update world regulatory domain
Dec  1 20:10:23 ubuntu NetworkManager[5144]: <debug> [1291234223.484258] [nm-manager.c:1194] user_proxy_destroyed_cb(): Removing user connections...
Dec  1 20:10:23 ubuntu NetworkManager[5144]: <debug> [1291234223.485116] [nm-manager.c:1223] user_settings_authorized(): User connections permissions: net 3, con 3
Dec  1 20:10:23 ubuntu kernel: [  408.358854] cfg80211: World regulatory domain updated:
Dec  1 20:10:23 ubuntu kernel: [  408.359384]     (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp)
Dec  1 20:10:23 ubuntu kernel: [  408.359912]     (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
Dec  1 20:10:23 ubuntu kernel: [  408.360431]     (2457000 KHz - 2482000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
Dec  1 20:10:23 ubuntu kernel: [  408.360946]     (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
Dec  1 20:10:23 ubuntu kernel: [  408.361359]     (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
Dec  1 20:10:23 ubuntu kernel: [  408.361710]     (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
Dec  1 20:10:28 ubuntu kernel: [  413.688007] wlan0: no IPv6 routers present
Dec  1 20:10:29 ubuntu ntpdate[5264]: no server suitable for synchronization found
Dec  1 20:10:30 ubuntu acpid: client 4689[0:0] has disconnected
Dec  1 20:10:30 ubuntu acpid: client connected from 4689[0:0]
Dec  1 20:10:30 ubuntu acpid: 1 client rule loaded
Dec  1 20:10:30 ubuntu NetworkManager[5144]: <debug> [1291234230.473063] [nm-manager.c:1223] user_settings_authorized(): User connections permissions: net 1, con 1
Dec  1 20:10:30 ubuntu NetworkManager[5144]: <debug> [1291234230.473117] [nm-manager.c:1265] user_proxy_auth_done(): Requesting user connections...
Dec  1 20:10:30 ubuntu NetworkManager[5144]: <debug> [1291234230.497349] [nm-manager.c:1223] user_settings_authorized(): User connections permissions: net 1, con 1
Dec  1 20:10:30 ubuntu NetworkManager[5144]: nm_setting_802_1x_get_pkcs11_engine_path: assertion `NM_IS_SETTING_802_1X (setting)' failed
Dec  1 20:10:30 ubuntu NetworkManager[5144]: nm_setting_802_1x_get_pkcs11_module_path: assertion `NM_IS_SETTING_802_1X (setting)' failed

Now to actually look at the code referred in the debug messages and see why switching vt triggers policy changes...