First of all, if everything is mathematically equivalent to an EU maximizer, then saying that something is an EU maximizer no longer represents meaningful knowledge, since it no longer distinguishes between fiction and reality.
I’m confused about your claim. For example, I can model (nearly?) everything with quantum mechanics, so then does calling something a quantum mechanical system not confer meaningful knowledge?
Are you making this argument?
P1: Quantum mechanics is well established.
P2: Quantum mechanics describes everything in low gravitational fields.
C1: So, calling a thing a “quantum system” doesn’t convey any information.