Preface: I'm not interested in debating this topic here. Therefore I'll be concise, abridged and probably glib.
Your term "assault", can legally, imply a prelude to battery. Maybe that's a stupid point.
And I do not wish to dismiss your concerns either.
However, if you endeavor to qualify the transport of potentially fatal materials as violence, such would be a highly abstract interpretation requiring an unprecedented overhaul of the present system.
If someone is caught planning a violent act, e.g. performing internet search queries for "how to do terrible x and accomplish terrible y, the rule of law doesn't permit immediately executing the individual. Traditionally, a trial ensues where possibilities of error and other critical considerations are made in order to ensure greater probabilities of a just outcome, hence Justice. An immediate threat and remote hypothetical threat are treated differently. If Bob knows you plan to kill him on Friday, but he finds you while you're doing laundry and kills you Thursday, while tactically legit, it doesn't work legally. Extrajudicial is what we might call this. But regular folks wouldn't earn the term.
But that's barely the surface. If transport qualifies as violence, then the users that contribute or essentially enable the entire cycle must be included. So now we are killing foreign boaters in the Caribbean and e.g. Hunter Biden on his jetski as he swirls around the Florida Keys high on fentanyl. We'll need to kill his hooker friend too, because she directly supports these transporters.
It gets much sillier from here, all the way until you kill Bill because he spent money at the same pizza parlor as the guy who sold the baggy that overdosed your friend.
And then comes the strange dynamics where you need to kill me because my self-righteous doctor won't prescribe me pain management for my cancer because xyz and I'm looking on the streets for some kind of relief.
But we needn't go that far. We can go back to the top and kill the growers. And their children which might aid and abet them. And certainly a few chemists here and there.
It gets way messier. If you fail to kill me, I might have a grudge. Because I was not trying to hurt anyone. I'm in pain and just want help.
While this all takes place, other artistically inclined persons superimpose their own values upon the law.
But really, a few guys steering a boat full of drugs is not violence. Certainly not an imminent threat especially after they've been identified. It's the potential for violence, but so is our trusty old proverbial hammer.