I highly doubt that Ben would have survived his injuries if they were consistent with the sort of punishment that he absorbed as Glory (Giles was, I think, just making double sure) but, no, don't think that they would have, considering their reluctance to forgive both Angel and Spike under somewhat similar circumstances. This assumes, of course, that Buffy had still died in the finale. Without her there to forgive Ben first, the others would have treated Ben the same way that they treated the aforementioned two vampires, once they had returned with their respective souls restored.
If Buffy were still alive, however, then she would probably have forgiven him if Dawn had survived also. If not, then the question would never come up, because she would have shredded Ben slowly in revenge for what Glory had done to her beloved brat sister.