1) Block with his arms extended? So you want him to break his arm? Schuster is generously listed at 215. Burfict is listed at 251. If Schuster tries to arm block him, he's going to lose.
2) Not block from an angle where the defender is defenseless? Not possible in the few milliseconds that this play developed. No way he has enough time to adjust anything.
3) Not launch himself? Look at the .gif above. He plants his feet and leans forward so that he leading with his shoulder. If he doesn't do that, he's the one that's going to get knocked out in the upcoming collision. It's called bracing, not launching. It's taught.
4) Not target the head and neck area? He lowers his shoulder specifically to avoid a head shot. Burfict lowers his head and causes the chin contact.
5) Something like... wait a minute, that's the only option Marshall had here. He also blocked someone blindside (literally a person unanable to see someone their side). This block was no "safer" than the one we're debating here. And BTW, it looks like Marshall might've clipped Lee's helmet a bit.