The part that strikes me is that when your dog swims up to the boat, obviously wanting to get in, to shove it off with a paddle is shitheartedly cruel.
Okay-so maybe a dog can
swim the whole distance. Maybe your kids could do the same, in PFDs. But if they swam up to the boat, and asked to ride, would you poke 'em in the face with a paddle and tell 'em to keep swimming?
If you take your dog on a river trip, you ought to have some way to accomodate it in comfort and safety, on your boat.
Here's a happy river dog, with her own D-deck on a Pack Cat. She's got a PFD, but it was a flatwater trip at low flow– I wasn't wearing one either.
I think if you re-read the original message, the issue is pretty clear.