Ummm... Just a woman's perspective here. I think the school issue is a hot button for many of us Moms.
Even when my kiddos were old enough to be in middle school, summers stressed me every year. Even though my H would deal with it sometimes, it was basically "my" thing to juggle. I did not want her just parked in front of the TV set all summer, and even with some flexibility from my employer I was a nervous wreck by August juggling camps, playdates, etc.
I did resent my husband for not having to worry about it, or thinking it was OK to plop them on the couch all day. So, I felt very torn...wanting to work and contribute financially, but also wanting my kid to have a good summer. On top of that... The laundry, making a decent home for your family and adequete nutritious meals that kids need -/ WOW, most women who work just come home to the 2nd shift of housework, kids, etc.
So although year round school may SEEM like an innocuous issue, it's one of my hot buttons. Being a GOOD mom is the hardest job on the planet. Especially if your spouse travels a lot and works all the time. Not sure about your sitch, but usually the W has to deal with these big school calendar issues.
Personally, I think it's great she felt safe enough to express this to you.
