I don't think that Algebra I in 7th grade would be a problem. The issue is whether your DS is willing to put in the time commitment and be subject to this constraint over the summer. I would not oversell it because it is crucial that he is fully bought in, particularly in the event of difficulties down the road (whether academic or otherwise).
We still don't know how much time/days is required over the summer. They will keep me informed. Nothing's in writing yet. Is this an example of an IEP? They haven't used this term but I've seen it on this forum.
Without overselling it my son is inclined to do this... I told him that his test grades indicate he knows the 7th grade material already, but not the 8th, because he hasn't been taught. But if he does the 8th grade gaps in summer he could learn Algebra in the fall. He just wants to know how many hours/days of summer are required. Me too.
So I am sitting tight waiting for summer specifics to give them a decision from my son.