Promises made, promises kept! Just dropped an update on the tool—now you can add your own custom text and play around with colors. Go ahead, make your banner pop!
If the pagers had been equipped with lasers that caused blindness, there is a Geneva Convention protocol going back to 1995[0].
I would like to think that the spirit behind that protocol is that the intent to cause permanent blindness in your opponent should be considered a crime. And not that it's not a crime so long as you don't use a laser to do it.
So you can put me in the camp of "this should be considered a war crime", even if it's not in any books yet.
If the pager was sent a message that would encourage the soldier to bring the pager to their face, it would certainly fall under an intentionally blinding attack.
Of course that's a bit of a troll comment at the end there. There are plenty of Linux distros still not using systemd. https://www.devuan.org/ as one example.