I think you were, I just hadn't had my coffee yet :-)
I don't use suspend that much on my desktops, I normally just hibernate, in which case it does go through the booting process when resuming, and if I leave my flash drive plugged in, it hangs the boot.
Suspend gets used a lot more on the laptop, but there I don't normally have external USB devices plugged in.
I have played around with suspend on the desktop, and I have encountered similar problems with suspend/resume not working right when certain USB devices are plugged in. I remember trying a number of different things I found by Googling, but I never could get it to work reliably without unplugging some of the devices before suspending. I think it involved udev rules, /etc/systemd/system scripts, and so forth, but nothing really worked.
So I will be interested to hear if you find an answer for this.