Very cool, looks like a ton of fun.
Without wanting to claim there is no risk associated with this run, it is in fact a very limited one (for an able body), as long as you have basic whitewater kayaking experience where balancing your body weight is key.
The banks of the canal are making sure the kayak stays in line with a minimum help of the paddle, eliminating the risk to go sideways, and the landing in a lake setting makes it very safe, with plenty of room in relatively calm waters, should you need to roll back up.
I would still have worn a helmet though, and hate to see the gouges and scratches at the bottom of the kayak after that...... it's going pretty fast!