That's a lot of naysaying for a boat that autonomously got itself from California to Hawaii successfully.
I'm saying: how sure can I be that the experiment originally intended to do exactly that? Go to Hawaii?
The pickup of drugs would be the most dangerous part. No one would want to spread it immensely in space nor in time. While I'm naysaying in context of smuggling, the boat is an amazing achievement.
It's a boat, not a submarine. The low profile makes it harder to detect from the sea. Not from the air, though.
At max 2-3 knots it can only go with the current (not against). Needs calm-ish conditions, if it is to reach the destination as opposed to any random place.