AITA for telling a friend his custody plan is stupid?

This is an automated archive made by the Lemmit Bot.

The original was posted on /r/AmItheAsshole by /u/Electronic-Bird-151 on 2023-10-07 00:36:30.

I, 30s female am friends with a couple, also in their 30s, Dan and Tina. I'm more friends with Dan since I've known him 15 years, but I've known Tina for 7 years. They have a 4yo daughter, Ally. Dan and Tina recently broke up and Tina wants to move back home to the west coast, we're all currently on the east coast. Naturally the topic of child custody for Ally came up while Dan was hanging out with my and my husband. Dan wants to propose that he and Tina each get 6 months of custody with Ally. Jan 1st-June 30th then July 1st-Dec 31st and it switches off like that every year. I asked what about Ally going to school next year? Dan said she'd be with one of them until end of December then fly across the country and spend the other half of the school year with the other parent. I told Dan that idea is completely stupid and will never work. You can't uproot a kid in the middle of every school year. No judge with any common sense would ever sign off on that agreement. Plus, Ally needs a primary residence for school, doctors, and extracurriculars and anything else. Dan didn't like being told that and ended up leaving before dinner. My husband says while he understands my views I was really harsh. I personally feel that arrangements would be an absolute nightmare for Tina, especially as she gets older and doubt any court would allow it. I did text Dan to apologize for my wording, but no response yet.

AITA?

Edit: I know I was harsh. I reacted to a surprisingly bad idea in a very poor manner. That said, that's been our friendship for years. We've always called each other out over things that were stupid or we didn't think through. Dan's called me out countless times and I have him. He's never actually been upset before.