I don't see how, because the barriers aren't clearly defined, they become irrelevant. There might not be a specific point where a mind is sentient or not, but that doesn't mean all living things are equally sentient (Fallacy of Grey).

I think Armstrong 4, rather than make his consideration for all living things uniform, would make himself smarter and try to find an alternate method to determine how much each living creature should be valued in his utility function.