I bank it on the OP a lot. This time of year here's how I would see the situation. Since you beat me to the hole. I will give you a certain amount of time to anchor up and work your baits at the head of the pool. Meanwhile I'll happily work the tailend of the hole. IMO, 20 to 25 minutes is plenty of time. Eventually though, I would want you to row through or bounce through, and either move on or walk your boat back up to make another pass. IMO, this time of year the aggressive chinook are sitting right at the head of the pourovers and pools, so I would also like a chance at presenting my gear through this same zone. After 20 or so minutes, I will ask you if you are going to work your divers through and mention I would not cast while you row through. I have encountered this situation a number of times and most of the time the boaters have caught on. On a few occasions they've actually worked on through, and 15 feet downstream got their takedown. Apparently the scour extended further back so the springers were laying deeper in the hole than they thought.

In your case, since you were in the fast water, walking your boat up the riffle probably isn't feasible. So feel free to park your boat and hit it with me from the bank with driftgear or whatever, if you still think the head has fish holding in it.

If the maggots in question walked in and started casting over your shiat right off the bat. Then they are in the wrong.

If I beat you to the hole and I am pounding the head; again, feel free to hit it from the bank with me. Or work your bait divers below me. Just don't drop your pick in the fast water and expect me to make two more casts and give up the meat. If you're willing to wait for 15 minutes anchored up (about 12 casts) and ask, I would definitely let you make a pass through the head. To be honest though this situation has never happened. This time of year most boaters see me standing at the head and drift on through.