Anna, I have to say I've never heard about waiting that long to neuter a giant breed dog, but that's why were all here on PT, to learn from one another!!
My friend has two male Malamutes and she had them neutered when they were about 7 months old. She researched the breed before she got them, and knows a lot about all dogs in general.
I'll have to ask her what she's knows about this.

Hey... I'm not all THAT far away, and Sierra would LOVE to have a new "boy toy" to play with while your gone!!