In "Three Men in a Boat" by Jerome K. Jerome, what are Montmorency's objections to the boat trip? Are they valid?

Montmorency is a fox terrier – the dog represented in the title, Three Men in a Boat (To Say Nothing of the Dog). By the end of Chapter I, the men have decided to take a trip along the River Thames. To be fair, the fourth member of the crew is granted a vote:

The only one who was not struck with the suggestion was Montmorency. He never did care for the river, did Montmorency.
“It’s all very well for you fellows,” he says; “you like it, but I don’t. There’s nothing for me to do. Scenery is not in my line, and I don’t smoke. If I see a rat, you won’t stop; and if I go to sleep, you get fooling about with the boat, and slop me overboard. If you ask me, I call the whole thing bally foolishness.”

So, the dog’s perceived objections are that (1) he would have nothing to do on the boat, (2) he would be bored by the passing scenery, (3) he was not one to sit back and smoke a pipe or cigar to wile away the time, (4) the boat would likely not stop when he would want to explore something, and (5) he could accidentally fall overboard while sleeping. A few of these concerns are well founded. Montmorency has nothing to do on the trip, and he may have been bored. He does not drop into the water while sleeping, however. He doesn’t anticipate any problems or interactions with the tea kettle, either. And when he does spy a water-rat, he is able to grab it and donate it to a project George undertakes in Chapter XIV. He does indeed participate fully in this journey, and he does stay with the three men for the course of their adventure. He may have even enjoyed the experience and may have forgotten his earlier protests, by the end.