This is so dumb.
"We had way more preorders than expected, in order to fulfill our preorders, we will be delaying in store sales until after preorders have been completed"
that would be such a simple solution. It's not like they are out any money either way, and pushing an instore sale date back to make other prior commitments work isn't a horrible thing, it just means that people who didn't bother to preorder won't get it day 1, but most who wanted it day 1 would have pre-ordered it anyway.