I doubt the Nats know for sure either way with Harper, but I guarantee 100% in his mind he is returning and I bet the team thinks that is likely while also preparing for him to not return. 2 days ago the report was he was able to walk without any limp. Yesterday the big wet blanket was he "wasn't close to running." Does that mean he can't run or just that they see no reason to push it at this moment? Clearly there is a timetable of what he needs to do when to get back by say the last week of September to get geared up for the postseason. There is no reason to push him ahead of that timetable. It's a matter of if he can meet that timetable or not, and that we just don't know.
As for Harper "hurting the team" when playing injured before, I don't know about that. First, different injuries can impact your ability to perform in different ways. Wahetever Harper dealt with last year might have been a lot more hampering to his game than say playing on a knee that is still a bit sore. We don't know that. I also think that Harper has to be quite a bit hampered to still not be our best option to pencil in the lineup. He is always going to be a guy who gets on base because even if he's not 100%, pitchers are still not exactly going to come right at him to find out.
I think it's prudent to not react to dramatically to each little tidbit about his progress. 1 day it might sound positive and the next it might seem negative, as we've seen the past 2 days. We do know that Harper wants to play. I don't see any risk of a significant reinjury to where he'd not be able to get healthy this winter. If he gives it a go and he's set back in a minor way, what's there to lose when you have a whole offseason ahead and are chasing a World Series? Harper wants that ring.