The first is that expected utility maximization isn't the same thing as utilitarianism.

The problem is that if I adopt unbounded utility maximization, then I perceive it to converge with utilitarianism. Even completely selfish values seem to converge with utilitarian motives. Not only does every human, however selfish, care about other humans, but they are also instrumental to their own terminal values.

These are surely really, really different things. Utilitarianism says to count people more-or-less equally. However, the sort of utility maximization that actually goes on in people's heads typically results in people valuing their own existence vastly above that of everyone else. That is because they were built that way by evolution - which naturally favours egoism. So, their utility function says: "Me, me, me! I, me, mine!" This is not remotely like utilitarianism - which explains why utilitarians have such a hard time acting on their beliefs - they are wired up by nature to do something totally different.

Also, you probably should not say "instrumental to their own terminal values". "Instrumental" in this context usually refers to "instrumental values". Using it to mean something else is likely to mangle the reader's mind.