The "utility monster" has ceased to be a utility monster because it no longer gets everything. It still gets more, of course, but that's the equivalent of deciding that the starving person gets the food before the full person.

This sounds like it could be almost as repugnant as a utility monster that gets literally everything, depending on precisely how much "more" we're talking about.

Edit: if I were the kind of person who found utility monsters repugnant, that is. I'd already dissolved the "OMG what if utility monsters??" problem in my own mind by reasoning that the repugnant feeling comes from representing utility monsters as black boxes, stripping away all of the features of theirs that make it intuitively obvious why they generate more utility from the same inputs. Put another way, the things that make real-life utility monsters "utility monsters" are exactly the things that make us fail to recognize them as utility monsters. When a parent values their child's continued existence far more than their own, we don't call the child a "utility monster" if the parent sacrifices themselves to save their child, even though that's exactly the child's role in that situation.