I don’t always have one on me while fishing and especially bowfishing but if a boat is going under then the only thing I’m grabbing for is a life jacket. That area of the river does have some good current for sure depending on how much they are pulling water and in the dark swimming for the “bank” could be hard if you can’t see which way the bank is at night. He may have been treading water as long as he could until he just couldn’t stay up.
A life jacket improperly worn can be worse than not wearing one. A friend of mine who works these accidents explained it to me, and I never would have known otherwise. Not saying that either is the case, just a reminder to be diligent to wear a life jacket and to wear it properly.