Yes, but neomycin is indicated for colorectal surgery, not cardiac surgery, and is typically used in combination with other antibiotics. Different surgeries require different antibiotics, which should be administered at least an hour prior to incision. Also, the dose of 0.2mg is way below the recommended dose to have any effect.
What struck me as random was the context in which it was prescribed, not the use of antibiotics in surgery overall. The doctor asked about the patient's blood pressure, was told it was low and after hearing that ordered an antibiotic as if it would help with what he had just asked about . I was expecting a medication like epinephrine and him draining the fluid to address issue.
Randomly administering an antibiotic for someone in cardiac shock