Problem with a Hal Varian Question from chapter 5
I think the answer to your question is that it would be a matter of Ralph's preferences. Perhaps he is indifferent to eating at 11:00 am or 1:00 pm, as you suggest. But he might have non-parabolic preferences (for reasons unspecified), and both this situation and the one you describe are consistent with his eating at 11:00 am, so the answer provided is a correct solution to the question asked. Perhaps the particular indifference curves drawn are a way to avoid multiple solutions (the author might have thought it simpler).

I'm going exclusively off the information in your post though, so I'm assuming that we do not know if Ralph has any preferences over time independent of how it implicitly affects the price he pays.