I am sorry NG, but you are wrong when you said they should have taken it immediately to the ocean. It may have been sick or it might have ingested some human made material that caused it to be disoriented and end up on a freeway in the first place. There had to be something wrong with it or was more of a pet or something. Why would it have gotten into the back of the police car all by itself so easily with no coaxing?
No, the most humane thing they could have done was just what they did do; unless you would have preferred they put it down.

Maybe they wanted to keep it?? Have it as their "police mascot?" LOL!

Why is there a need to bring the sealion back to the station for evaluation? This is even more of a joke. They should get it back into the sea immediately instead.