By my reading, that contradicts your assumption that our utility is a linear function of the number of stars we have consumed. (And, moreover, you seem to say that never running out of starstuff is a conservative assumption which makes it less likely we will go seek out more starstuff.)
No, because maximizing utility involves tradeoffs. Being expansionist means expanding instead of doing something else.
By my reading, that contradicts your assumption that our utility is a linear function of the number of stars we have consumed. (And, moreover, you seem to say that never running out of starstuff is a conservative assumption which makes it less likely we will go seek out more starstuff.)