So I tried removing it by editing the desktop file, copying it to ~/.config/autostart, and even removing the /etc/xdg/autostart/ desktop file entirely. No love. Still starts.
Then I tried this (removing execute permission):
No love, the system becomes unresponsive while systemd keeps trying to start this thing that won't start up. Spams the log file too.
There was a variable at one time that paid lip service to shutting this thing down: NO_AT_BRIDGE=1.
Yeah... nada. Still starts.
I have grepped for the executable name across the entire disk and moved every instance of anything that appears to call this. It still starts it, or tries to. Removing the package, removes lots of other things that should not depend on it in the first place... sigh.
Next I go through every file in the spi2 package to see if I can figure out how to stop systemd from ever trying to start this.
Far more effort than should be required to remove something unneeded and unwanted by 80% + of the userbase.