Based on current events, Riv is going to need to change plans - with Steel's getup, there is no way in hell DD'd plan is going to work. What does he have that will let him ambush someone in power armor?
I just need to get close, and an inch of exposed skin, and he's toast. He'll barely have time to notice he's being assassinated. Substitution is something else though.
If I understand the plan properly, the idea is that we go down and slaughter some defenceless innocents, and then the survivors go back to the ship for more partying. I'm guessing that the weapons that we'll be using on said innocents are kindly provided by steel?
The way I see it, our best bet is to take him either in flight or on the ground, and then steal his dropship ID codes (Curie!) to allow us to pretend that the downed shuttle is someone else's. Or, we remove him on the ground in the chaos, and then either steal his dropship to get back up, or swap the codes with ours. Either way, everybody thinks that a few insignificant guests have died, and that Steel is safe.
AG, Steel has a security detail with him at all times. Their attention is on Steel and the other guests, not so much on each other. How easy would it be to take one of his guards out and steal his uniform? Right. Now. Before the dropships are fully loaded?
The Truth of steel also makes for a great target, with all the attention on the ground, it would be easier to sabotage it. (We could even envisage getting it to shoot Steel out of the sky on the way back up.)
Also: What can I tell about Steel's power armor? Is it state of the art like I expect?