Won't be able to scout in-person, no, but they will be able to watch tape and a "pretty solid" idea is one thing but having the actual list and being able to put together a real strategy in terms of potential team building seems like the kind of thing that should be done with at least some prep time.
Even in terms of tape, there's nothing that's stopping them from having watched and analyzed game film on all the players that have a possibility of being available. A few more days isn't going to really provide much more information there.
McPhee was interviewed around the All Star Game, and said he and his front office team had already been going a wide range of scenarios based on potential availability lists. It's probably fair to say that, barring any massive surprises, they'll have done more than enough prep by the time they get the official lists. At that point, the discussions will be which already developed strategy they'll choose to follow.
Honestly, outside of some extra time to negotiate trades, anything that can be accomplished in those extra few days can and should be in the process of being accomplished already - to the point that the benefit of those extra days is pretty minimal - and opens up more possibility of paralysis through analysis.