Middle school is a whole different animal from elementary school. Here too, it seems to be all about organization and obeying. It think it's wonderful that they are being 'take charge' about expecting the kids to come on Saturdays if they aren't doing the work during the week. Consequences - Yippee!
I think that the last thing a kid needs is to be excused 'because they are gifted.' And the 'consequence' spending time in school undersupervision is natural and logical - it's not as if they have to write 100 times, "I will do my homework.' In other words, it doesn't suprise me to hear about a group of gifted kids who have just been coasting along suddenly realizing that a lot more is required of them. Better now than when they are off on their own in college.
A lot of teachers put thought into their homework assignments and genuinly believe that if the students do the work before class, they will have a more meaningful experience during class.
All this is assuming that the homework isn't awful busy work just for the sake of keeping the kids chained to their desk afterschool. Since the school has differentiated for your kid, that gives me hope that they aren't missing the LOG boat for the others.
As a parent, I would be cheering wildly if someone took my son's development of work ethic as seriously as I do, and not just saying "Oh he's smart, that will get him through." Just think how proud these kids will be in a few weeks or months when they see that they school means business, and they start showing up for class with their work completed.
There is such a thing as all the teachers independently assigning big projects on the same day, and the school will probably be amenable to dealing with that if enough parents complain. There is also such a thing as teaching the children how to break down the big projects into managable steps, and that's a good thing too. I also like it if teachers post on Friday's what the week's homework will be, so that the slower ones can get a jumpstart over the weekend. I don't know what is 'a huge amount' of homework, but I know 4th graders who spent 45 minutes Monday through Thursday.
You've already voiced your opinion, I would reccomend that you not step into this at this time. Of course it's always good to encourage parents to share their concerns with administration instead of you, but I would be a little skeptial if they try to draw you in to their lament.
So glad to hear that your kids is being accomdated - Yippee!
Grinity
