I'm a natural-born cynic but that sounds like a standard delay-the-user response tactic to me.
The annecdotal evidence does suggest a software problem in this case, but if it weren't for that I wouldn't be happy with that response because they haven't actually resolved the problem as far as the user is concerned or made any promise or guarantee of when it will be resolved.
Always beware when companies tell you to wait. It's usually a deliberate strategy to slow, limit or discourage the user from pursuing their rights, not least a speedy resolution. It's in their interest to limit and reduce the rate of returns and replacements. You shouldn't have to wait if you've got a malfunctioning product, especially a high-end, premium phone from one of the world's richest companies.
Apple receives enormous benefit from the confidence and good-will of its customers, and some of this was rightfully earned, but I'm concerned about Apple becoming increasingly user-hostile in the search for profits. My confidence in the company is faltering and as such I'm less willing to accept vague, non-committal responses like that. My follow-up question would've been "when will the fix be released"?
Remember, Apple doesn't even allow you to downgrade to iOS 9 so they've denied that potential resolution from the user. If the problem was enough to seriously affect my use and confidence in the product (and random shutdowns would certainly do that) I'd be seeking an immediate fix. If that amounts to a replaced handset then so be it.
