Michael O'Loughlin's ankle injury means Hall is a timely addition to the Swans forward structure, but Roos said his spearhead would have returned in any case after feedback from club psychologist Grant Brecht, who's been overseeing Hall's recovery.
"I was thinking about this last night and I thought that'd come up. If people think that … in a way they're calling me a liar. It's a bit of a slur on my character," Roos said on Thursday evening.
"I really don't like that. We've been pretty open and honest about it (Hall's recovery) the whole way through.
"So people who don't believe what I've said are questioning the integrity of myself and the integrity of the footy club. It's disappointing."
Roos was loathe to say whether this was Hall's last chance after two charges saw him suspended for a total of weight matches this season.
Since his last suspension in round 14, Hall has been unavailable for selection pending the go-ahead from Brecht.
But Roos was clear of what he expected of the 31-year-old from this point on.
"We don't want to see the things we've seen this year. To be clear, Barry's got to play a physical style of footy. But the two incidents we've seen this year, we don't want to see again.
"Hopefully Hally understands, and we think he does, the implications of what he's done this year."
As for Hall's mental approach, Roos stressed the importance of "taking the pressure off Hall" not only for Saturday's clash but for the rest of the season.
"He doesn't have to kick five goals. He is part of the team. If he does kick five then great but if they double-team him and he drags players away to give space for other forwards then he's done his job for the team.
"The Crows will double-team him so we don't expect him to dominate the game. He'll probably take (Ben) Rutten and (Nathan) Bassett, so Saturday night will be a good test of him being able to focus on the team."
Roos added that he has noticed a difference in Hall over the last week.
"He has really taken responsibility and that needed to happen. And it's an important shift in taking responsibility for his actions."
Roos added that Hall will not be appearing in front of the media again this year.
