The monster you should let eat you
bbc.com
bbc.com
First, define happiness.
Then define it in the context of species that experience it differently.
Then, define how you measure a quantity of it, in a comparable unit.
Then, define how you can compare them.
Gooooood luck.
Moreover, if this kind of entity exists (and it is described in the article as highly incomplete/unbalanced beings - but again, there's a parti pris towards utilitarianism, so why wonder), unless there's huge empathy and ethics components in it, there will be no argument.
Who ever asks a tree if it is ok to be chopeed down as to build a house or serve as a one-time Christmas tree?
Where utilitarianism reproduces intuition, it's redundant. Where it contradicts intuition, it doesn't do any good to say "Well, under utilitarianism, that's just fine". It's a good framework for discovering and analyzing our internal contradictions, but it's often treated as a pragmatic construct, and I don't know how well it serves there. You still need to check all of your conclusions against intuition, so it hasn't saved you any effort, and you risk being able to say "The model says this I'm going to follow it slavishly", leading to Repugnant Conclusions.
https://en.wikipedia.org/wiki/Mere_addition_paradox
Even if a perfect utilitarian model existed, we don't possess it. So as appealing as utilitarianism is, I think of it more as a useful academic strawman rather than a real engine for moral conclusions.