Interesting, I have the same dbux-proxy package. On my system it seems like it’s more embedded and harder to remove though. Not sure if going through with this will end up pruning 50% of my install.
$ pacman -Q | grep dbus
dbus 1.12.20-1
dbus-glib 0.112-1
dbus-python 1.2.16-4
kdbusaddons 5.82.0-1
lib32-dbus 1.12.20-1
lib32-dbus-glib 0.112-1
lib32-libdbusmenu-glib 16.04.0-4
lib32-libdbusmenu-gtk2 16.04.0-4
libdbusmenu-glib 16.04.0-4
libdbusmenu-gtk2 16.04.0-4
libdbusmenu-gtk3 16.04.0-4
libdbusmenu-qt5 0.9.3+16.04.20160218-5
xdg-dbus-proxy 0.1.2-3
[usr@laptop ~]$ sudo pacman -Rns xdg-dbus-proxy
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: removing xdg-dbus-proxy breaks dependency 'xdg-dbus-proxy' required by flatpak
:: removing xdg-dbus-proxy breaks dependency 'xdg-dbus-proxy' required by webkit2gtk
[usr@laptop ~]$ sudo pacman -Rns flatpak webkit2gtk
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: removing webkit2gtk breaks dependency 'webkit2gtk' required by gufw
:: removing flatpak breaks dependency 'flatpak' required by pamac-flatpak-plugin
:: removing webkit2gtk breaks dependency 'webkit2gtk' required by yelp
:: removing webkit2gtk breaks dependency 'webkit2gtk' required by zenity
:: removing yelp breaks dependency 'yelp' required by pulseeffects
:: removing zenity breaks dependency 'zenity' required by steam-manjaro