OK, nothing good about this story. Homeless guy jumps in against officer's advice and then drowns while the cop refuses to jump in to save him. I'm sure the autopsy and toxicology report will reveal a lot of issues.
A potential drowning is a very serious situation even if the rescuer is a skilled swimmer and trained in life saving.
Fully dressed in the water while dealing with a panic stricken person could easily result in both of them drowning.
I probably would have jumped in to attempt to save the guy but I'm a skilled swimmer and not about to assume the officers have the same skill level as I have.