is that reasonable?

This depends on if you really think the extra week is going to change his mind on giving you a good reference. Personally, it sounds like he's already made up his mind and will throw you under the bus at the first opportunity. Plus, having gone through a similar situation, that extra week can be really awkward. Your boss will try making comments about you not giving your full effort, "one foot out the door", and all that annoying banter.

I'd say you've done more than enough to give them a reasonable window to hire a replacement. He'll claim his anger is due to you breaking your trust, but it sounds more like he knew he was getting you for a deal, and now that you've realized what you're actually worth, he knows he can't compete. At the end of the day, you have to realize that as nice as they act, you're expendable to them. So be polite, but do what's best for you always, and any reasonable potential employer/interviewer would agree with that attitude.