I’ll try to tackle these paragraphs one at a time.
First: Shago’s demon is only throw invincible, so the setup off sweep and lvl 4 battery ender will beat the demon. I made sure to test that. This is because in these instances the jump in or the fireball hit meaty, causing him to be hit out of start up.
Second: safejumps are just another option on a knockdown. Any instance where you land a sweep, you could’ve walked up and did a ground meaty or whatever instead. The strength of a safejump is that it forces respect and works towards conditioning. For example, let’s say I safejump a player a few times in a match. The player might finally realize, “maybe I shouldn’t reversal, and just block.” Once I’ve conditioned my opponent to respect on wakeup, I can be a bit more daring in my mixups, such as going for an empty jump low, empty jump throw, or whatever else I may decide. They’re a way to open the door the stronger oki possibilities, they aren’t necessarily the be all end all (unless your opponent is a huge moron and insists on DPing it every time, in which case you can just keep doing it and murder them)
As for the opponent’s options, they do have a few. The obvious one is to simply block it and take the pressure, which I’d argue you rightfully earned off a knockdown anyway. Since this is KI, they can always try to Shadow Counter after blocking the jump in. Another thing they can do is backdash on wakeup, but if you anticipate it, you can always chase the backdash with something or even OS it. As for if a safejump crosses up, it depends on the setup in question. I will say that if you happen to land the sweep particularly close, you will end up crossing up when you jump forward when you pass over them.
The crossup itself is the “oki.” Oki, or Okizeme, is just a term to describe the wakeup game, or stuff you do on the opponent’s wakeup. Consider this: in even a game like Street Fighter 2, if I knock the opponent down I have a couple options. I can jump at them and even decide to crossup, forcing them to guess left/right, or even empty jump and go low. This combination of decisions I can do is the oki game itself. As for what to do if it gets blocked, you have frame advantage and thus can apply pressure in whatever way the character does so.