I looked at Timatic (the system that tells airline agents what documentation you need) and it indeed does not say that you're required to have a negative test, just that you're subject to a test and quarantine on arrival if you do not have a negative result. So the agent was clearly wrong about "the verbage on her computer."

You say that they're offering you "nothing for the return home." Did you find a way to get to Aruba, or just return home immediately after you were denied boarding?