How dare he ask other people to use the software he wrote.

I think "ask" here is the wrong word, and you know it.

I'm curious to know what kind of leverage he had over the distros where it wasn't just "ask". Any suggestions on where I can find some info?

Let's say you're right. What kind of "political" leverage Lennard had to convince distros to use systemd?

All he would've needed was the support of RedHat management, after that everything falls into place: most Gnome contributors work for RedHat, so they can convince Gnome to follow a particular direction and hard-depend on systemd. Then most distributions are under pressure from their userbase to support Gnome (because of a legacy of politics and FUD about the KDE license, because a minimally-configurable environment is popular with the kind of large, inflexible organization that buys expensive support contracts, and because it's actually quite good software) and are therefore also obliged to hard-depend on systemd.

It's in RedHat's interest for software that's currently portable to FreeBSD or especially to Solaris to become tied to Linux. This wouldn't be the first time RedHat has adopted anti-opensource methods out of fear of Oracle - compare their policy of deliberately obfuscating the history of their kernel source.

Thanks for the explanation. I never thought about this before. It makes senses, but it is scary. I hope you're wrong. :)