First and foremost, my heartfelt condolences. I have also had to be at the riverside where a paddler died. I know what you're going through.

Gashed helmet? Bruises on the forehead or temple? It's a bit odd that such an experienced paddler could not get out of his boat, which makes me ask if perhaps it was because of some confusion or stunning due to a hard head rap. He did try to roll, though, and it's hard to figure how he could have enough presence of mind to do that and then be unable to exit the kayak. Concussion can be somewhat unpredictable and may take some time (not much in this case, but not zero) to develop.  This kind of "sudden inability" sounds like some other head injury reports I've read, but in those cases no purposeful actions intervened between the original cause and the inaction.

I've forwarded a copy of your report to Charlie Walbridge, but if you can take the time (and it's not too hard on you mentally to write it) please send as detailed a description of the incident as possible to Charlie (ccwalbridge@cs.com).  Thanks for taking the time in what must be a very trying emotional time for you to write what you have; we in the SWR community will learn from it.

Please also consider consulting a critical incident stress debrief (CISD) counselor; this kind of incident can be very hard on the survivors. Many companies will pay for employees to visit one if they need it, and if you don't know where to find one, call your local fire or police departments and ask. They use these folks all the time and should be able to give you some leads to counselors in your area.