The worst they could do is say no. I am no expert, but I would DEMAND no homework. I would say that it negatively impacts him, not only his grades but his self esteem, it makes his depression worse, and he is simply not capable of starting it or completing it right now. You are not willing to make your home a battleground for the very few hours you have as a family. Family time is also important to his development and to his mental health, in fact it may be MORE important to his development than those homework assignments. School can figure out a way for him to do any assignments during school hours or they can exempt him from the assignments. Period. It is considered an accommodation for his illness.
I know other parents have gotten such exemptions, but I don't know what arguments they used. You might try googling 'homework exemption for high school IEP' to see if that helps if you don't get answers that are helpful here. You also might try wrightslaw forums for help, though I haven't ever used them.
I would ask for any and every thing you think would help. I would google the types of things you think would help, or "IEP services to help with task initiation" and "IEP services to help with turning in homework" and "IEP services to help with task completion" and "measurable IEP goals for high school".
Make SURE you do not sign that IEP right away. Bring it here and let some of the others look at the goals etc... They will have a better idea of how good it is. Lots of schools use goals that are not measurable and then say the child made progress and doesn't need the IEP long before the child is actually able to function without the IEP. It leaves the parent with little to fight with because the goals are so unmeasurable that no one can say anything about them one way or the other. I don't have examples, but I know it happens frequently. I drove our school system crazy with insisting on measurable goals and not "will be on grade level". What grade level? Kindergarten? Fifth grade? Junior in college? If you mean a certain grade, put it in there, why is that difficult? I really thought one teacher was going to hit me when I asked her that for the third time. But it was the third time that she wrote the same goal "will be on grade level" and I had just asked her what grade level and made her rewrite it twice in the 2 sentences before that. So how did she think I would ignore sentence 3? Talk about someone who needed an IEP, and I do NOT mean my child!
I also learned to go back about 2-3 months after the IEP meeting and ask for a copy of the IEP. I usually said I lost mine and needed another copy. Why? When my son ended up in the psychiatric hospital in 6th grade, I hand delivered the IEP to the hospital. His special education teacher never thought I would read the IEP before I gave it to the hospital. I did read it. She altered it and forged my initials in several places and my signature. She was a bad forger, but she never expected me to look at it, or for anyone else to question it. She wanted to cover herself for letting Wiz go online when all of his computer privileges had been revoked at school. She also let him have access to some things that helped drive him to psychosis and she was trying to hide it. The hiding actually showed us what she did and proved it. Ever since then, I go back and ask for a copy of any IEP or 504 a couple of months later to see if it is actually the same as what I signed way back when.
I hope some little bit of what I replied helped. I wish you the best with this. If you have problems with the IEP meeting, get an advocate. You can usually find out were to get one on the state board of ed website.